Campaign 2018 begins the final stretch this week. All but a few states have finished their primaries, and the general election ballots are set almost everywhere. The stakes are difficult to overstate.

Republicans today control the White House, the House and Senate. President Trump dominates the scene. But Democrats could take control of the House in November and dramatically alter the politics of Washington for the next two years. The coming weeks will see tens of millions of dollars spent on torrents of negative ads, leading up to the Nov. 6 balloting.

What follows is a look at some of the key questions about the election, based on comments offered by several dozen political strategists from both parties.

Question 1: Is there really a blue wave ready to crash onto the House Republicans or are Democrats overconfident?

History says Democrats will gain seats, but is there really a blue wave about to sweep Republicans from power in the House? That’s the overriding question for the 2018 midterms, because if that happens, the second half of Trump’s first term will be significantly different from the first half, for both the president and his party.

Democrats need to pick up 23 seats to take control of the House. Given everything known at this point, the question is: Why shouldn’t they be able to do that? The Cook Political Report, for example, lists 38 Republican-held seats as toss-ups or worse, and 27 GOP seats in the “lean Republican” category, which means Republicans have the advantage but the races are competitive. The number of Democrats in toss-up or worse? Just three, with two more on the “lean Democrat” list. That imbalance speaks volumes about the climate.

The party that holds the White House almost always loses seats in midterm elections, especially during a president’s first term, and especially when a president’s approval rating is below 50 percent. Other indicators speak to the Democrats’ advantage. Through a series of special and regular elections since Trump’s victory, Democrats have shown themselves to be more energized. They have outperformed Hillary Clinton’s vote percentage in district after district.

Beyond that, there are Republican retirements. The Cook Political Report’s David Wasserman counts 41 GOP-held seats with no incumbent on the ballot, including 23 because of retirements. He said it’s the highest number of Republican open seats since at least 1930 and perhaps much longer. That’s significant because open seats are easier to flip than seats with incumbents.

But will there be a blue wave (enough to get 23 pickups), a blue tsunami (Democratic gains of well beyond 25), a blue tornado (picking off Republicans in a more haphazard and less predictable pattern), a strong tide, a riptide or just a blue surge (that would keep Democrats short of their goal)?

Strategists differ on just how powerful and pervasive the forces are ahead of the November balloting. A few Republicans believe their party will still hold the House in January; most are far more worried. A few Democrats believe the wave will be a tsunami, pushing pickups into the range of 35 or 40 seats; others are cautiously confident. Republican pollster Ed Goeas offers a simple definition: If Democrats win the House, it was a wave; if not, it wasn’t.

The range of expectations gives some sense of the scars left from 2016, when few predicted Trump’s victory. People who follow elections for a living are still burned from that election. Republican pollster and GOP strategist Scott Reed said the blue wave is overblown and predicts that Republicans will hold their losses to just 15 seats. Other Republicans, on the record, are more bearish. Pollster Whit Ayres said that if Republicans manage to keep control of the House, “they will have bucked a powerful historical trend.” GOP strategist Sara Fagen wrote that the combination of factors at play “means Democrats will be able to pop the champagne corks on Election Night.”

Question 2: What is the most plausible path for Democrats to win the Senate — and how plausible is it?

There’s a path, but most strategists say it’s not all that plausible unless November becomes a huge Democratic wave. It’s all about geography. The battle for control of the House is playing out on terrain favorable for Democrats: There are several competitive seats in very blue California, for example. There are competitive races in suburban districts. A new set of district lines in Pennsylvania gives Democrats the prospect of adding seats. Etc.

In the Senate, it’s just the opposite. The Democrats are playing defense on Republican ground, and they face what might be the worst map in generations. GOP strategist Karl Rove took a look back and concluded that this is the worst map for any party since the country began electing senators by popular vote in 1914. Will Ritter, another GOP strategist, jokes that it’s the best map for Republicans “since they moved the Senate from Philadelphia” (which of course was before the modern Republican Party even existed).

For starters, of the 35 seats in play this year, nine are in Republican hands. The rest are held by Democrats (or, in the case of Vermont, by an independent, Sen. Bernie Sanders, who caucuses with the Democrats). Add the fact that 10 Democratic-held seats are in states Trump won in 2016, with five of those 10 in deep-red states.

The good news for Democrats is that a few of those incumbents in the purple states won by the president are considered in good shape. The bad news is that some of those in deep-red states are highly vulnerable, among them North Dakota’s Heidi Heitkamp, Indiana’s Joe Donnelly and Missouri’s Claire McCaskill. Democrats feel a bit better about West Virginia’s Joe Manchin III and even better about Montana’s Jon Tester, but Trump won Manchin’s state by 42 points and Tester’s by 20 points. Add to the list of worries for Democrats the state of Florida, where Sen. Bill Nelson faces a serious challenge from Gov. Rick Scott (R), who can spend his own fortune in one of the costliest states in the country.

So what’s the path for Democrats? The first step is to protect all or virtually all those vulnerable incumbents. Bruce Mehlman, who worked in the George W. Bush White House, suggests that’s not out of the question. He did a study looking at 333 Senate races in 10 midterm elections dating to 1978. He concluded that what matters most “is not being from the party that holds the White House, regardless of a state’s partisan lean.”

If Democrats manage to protect their incumbents, they have to win only two more seats. Prospects are considered best — but not certain — in Nevada and Arizona, followed by Tennessee. A long shot is Texas, where Democratic Rep. Beto O’Rourke has captured the imaginations of Democrats as no other candidate this year. He is giving Republican Sen. Ted Cruz a strong challenge but is still the underdog.

Republicans are confident that they will still hold the Senate in January. “There isn’t a plausible path,” one strategist said. “Every night I dream of trading maps with my Senate colleagues,” said another Republican who is focused more on House races. Dick Wadhams, a Colorado-based GOP strategist, believes his party will emerge with more Senate seats than it has today. In that case, he said, the blue wave “will be tinted with purple haze.”

Question 3: How closely should people watch the gubernatorial races and why?

The gubernatorial races are the opposite of the Senate races. Of the 36 contests this fall, 26 are in states controlled by Republicans, nine by Democrats and one by an independent. More than a dozen races have no incumbent, thanks largely to term limits. Democrats hold 16 governorships today and will gain ground. The question is how much?

Though they will get less attention than they deserve, the gubernatorial races will have an impact on politics at the state and federal levels lasting well into the next decade. That’s because, after the 2020 Census, governors who are elected in November will play a key role in the next round of redistricting (at least in the states where legislatures and governors still control the process).

Republican gubernatorial and state legislative victories in 2010 gave the party power over redistricting, which in turn produced congressional maps that have given the GOP an added advantage in maintaining its House majority. For that reason alone, the stakes are sizable.

Beyond that, gubernatorial races are important for shaping the 2020 presidential campaign. For a political party, having the governorship doesn’t guarantee that its presidential nominee will win that state, but it’s a boost nonetheless. Having the governorship is critical to building infrastructure in political parties, and Democrats have been weakened dramatically by their lack of power in many states.

Strategists are looking specifically at Ohio and Florida, where there are toss-up governors’ races in open-seat contests in states that have often been the biggest presidential battlegrounds in recent years. Other battleground states with competitive gubernatorial races include Wisconsin, Michigan, Iowa and Nevada.

Governors often provide what one strategist called “an intellectual idea bench” for their parties, a place where conservative or liberal agendas can be tested and refined before going national. Both parties expect that the outcomes this fall could provide early signs of what voters are looking for in the future.

These races also could produce historic changes. In Georgia, Democrat Stacey Abrams is seeking to become the first African American female governor in the country’s history. Jared Polis, the Democratic nominee in Colorado, would be the first openly gay man elected to lead a state. Democrat Christine Hallquist of Vermont is the first transgender nominee for governor from a major party, but she is a decided underdog in her race.

That points to one reality in the governors’ contests: the strength of Republican governors in blue states. In addition to Vermont Gov. Phil Scott, Maryland’s Larry Hogan and Massachusetts’s Charlie Baker are among the most popular governors in the nation. Both are favored.

One question about the gubernatorial races is whether the candidates, particularly Republicans, can insulate themselves from national forces. The issues in these contests are often more state-specific, but because Trump so dominates the environment, some GOP strategists fear that, if there is a national wave, it will hit governors as well, as it did against the Democrats in 2010.

Question 4: How much will Robert S. Mueller III, Michael Cohen or Paul Manafort matter to the voters in November?

Begin with a caveat, which is that no one knows what will happen with the special counsel’s investigation between now and Election Day, although the window for a definitive report from Mueller is just about closed, given Justice Department guidelines (contrary to James B. Comey circa October 2016).

Strategists in both parties see the Mueller investigation and all its parts — including the Manafort conviction and the Cohen plea agreement — as more or less already factored into voters’ thinking. Only a smoking gun could change that, say Republicans.

They believe that for most voters, the Russia investigation is mostly background noise. GOP pollster Robert Blizzard wrote: “I’ve conducted over 100 in-person focus groups with voters since Trump was sworn in. Not a single respondent has ever brought up anything related to investigations or Russia. Not one.”

Democrats don’t fundamentally disagree but note several other things that could be advantageous to them. One is that the revelations are adding to anti-Trump sentiment and helping drive Democratic intensity. Second, the investigation, along with other ethical scandals involving Trump administration officials or GOP members of Congress, offers an opportunity to focus on corruption in Washington as a motivating issue.

The counter is whether any of this will end up motivating Republicans, too. As GOP strategist Scott Jennings wrote, “There’s also the possibility of a boomerang.” By which he means that if the focus spills from corruption to impeachment, Democrats could suffer, as Republicans otherwise disinclined to vote in November become energized.

One Democrat, who spoke on the condition of anonymity to give a more candid observation, wrote, “This is something we control and we’re not doing a good job with it.” Another Democrat said, “If Democrats are talking about any of these guys, they are talking about the wrong things.”

As for Manafort and Cohen, Republican strategist Alex Conant may have put it best when he said that if Mueller makes no significant moves between now and Election Day, “most voters will have forgotten about Cohen and Manafort.”

Question 5: Which will do more to shape the outcome, Trump’s approval ratings or the strong economy?

Presidential approval has proved to be a more reliable indicator of midterm elections than the economy, and most of the strategists looking at November agree, but with some cautions.

With history as a guide — which is always risky with anything involving the politics of Trump — a presidential approval rating below 50  percent and especially below 45 percent spells trouble for the party that holds the White House, even if the economy is good. Trump’s approval rating in the current RealClearPolitics average is 42.2 percent. (That includes the latest Washington Post-ABC News survey, which pegs his approval at 36 percent, on the low end of current polls.)

Republicans do not discount the importance of this but see contrary signs that could offset Trump’s weak numbers. “We’re seeing stuff that does not quite look typical compared to past Democratic off-year wave elections,” Republican pollster Bill McInturff said.

Among them: rising economic confidence, higher economic ratings for the president than his overall approval, rising “right direction” numbers and declining “wrong track” numbers. Another has been Trump’s generally stable approval ratings, which have changed less since he was inaugurated than has been the case for most presidents. McInturff and others at Public Opinion Strategies concluded that the president’s approval rating needs to be at least 45 percent in Election Day exit polls for Republicans to have a chance to maintain control of the House.

Republicans wish the president would do more to link the economy’s strength to the work of Republicans in Congress. But would it matter if he tried? As GOP strategist Josh Holmes wrote: “Our politics are all Trump. Our sports are now about Trump. Everything is about Trump.” He said the economy provides justification for wavering voters to back Republicans but added, “Ultimately, the president casts the biggest shadow by a long shot.”

Question 6: What is this thing pollsters call the generic ballot, and if we can’t trust it, what should we look at?

You’ll hear a lot about the “generic ballot” question on surveys between now and November. It asks people whether they’re likely to vote for the Republican or the Democrat for Congress in their district. It uses no names of candidates, hence the term “generic.”

It’s widely used and often cited, but there are reasons for consumers to be skeptical about what it says. This year it has bounced up and down, sometimes showing significant, even double-digit leads for the Democrats and at other times showing a narrower lead.

Some strategists say it’s unreliable until just before the election. Others say it’s a barometer of the national mood but tells little about the specific districts that will decide the outcome of the election. Jefrey Pollock, a Democratic pollster, said that in individual districts the generic ballot works as well as using the names of candidates, because of tribal voting, but nationally it’s not reliable.

Regardless, one thing to remember is this: Given the advantage Republicans have in the House because of gerrymandered districts and because of geography (Democrats are more clustered geographically, while Republicans are more spread out), Democrats need a clear lead in the generic ballot and a clear lead in the national popular vote for the House on Election Day to have a chance of taking control.

Question 7: Will this really prove to be the Year of the Woman, and what does that mean for politics?

Lots of different groups of voters could play a crucial role in determining the results in November. African Americans had an enormous impact on the victory by Democratic Sen. Doug Jones of Alabama in his December special election against Republican Roy Moore. Young voters favor Democratic policies by wider margins than do older voters, but if many of them stay home, as is often the case in midterms, their influence will be vastly diminished.

Trump voters are another key group, and the president is working overtime to keep his base (which is not identical to the GOP base) motivated, warning of dire consequences if Democrats take control. He is more invested personally in the midterms than many presidents are.

Without discounting the significance of any of these groups of voters, 2018 is still likely to be remembered as the Year of the Woman. In many ways, it already is.

One reason is that more women are more involved at more levels of politics. Amy Dacey, a Democratic strategist, said the activity level includes more women “running for office, women operatives, women activists and women voters — all of them will have an impact on this election.”

The Center for American Women and Politics at Rutgers University has kept tabs on female candidates, and this year has broken all records. A total of 476 women filed to run for the House — the previous record was 298 — and 251 are still in the running. In the Senate, 53 women filed — beating the old record of 40 — and 26 are still in the running. Sixty-one women filed for governor — the old record was 34 — and 18 are still in the running.

Another reason that this is the Year of the Woman is that women, more than men, have reacted far more negatively to the election of Trump and are providing the energy behind many candidates. There are plenty of women who back the president and do so strongly, but many more women oppose him, and the intensity of that opposition is greater than among men. In the latest Post-ABC poll, 66 percent of women said they disapprove of Trump’s performance, compared with 54 percent of men.

White college-educated women are moving to become a key part of the Democratic coalition. At the 100-day mark of Trump’s presidency, a Post-ABC poll found that 40 percent of white college-educated women and 51 percent of white women without college degrees approved of his performance in office. Today, 23 percent of white college-educated women approve of Trump’s performance, as do 49 percent of white non-college-educated women.

Question 8: What will the results in November tell us about 2020?

At one level, the results will say nothing definitive about what will happen in 2020. Presidents Ronald Reagan in 1982, Bill Clinton in 1994 and Barack Obama in 2010 suffered major losses in their first midterm elections (Clinton and Obama saw control of the House flip to the Republicans) and still went on to win reelection. Be wary of post-election predictions.

Yet there will be much to learn about the state of the country and the parties based on who wins and who loses. If Democrats have a very big election, the implications for Trump are potentially significant. A Democratic House means investigations and public hearings. The pending report from Mueller’s team makes for an unpredictable dynamic, with an internal Democratic debate likely over whether to focus on impeachment.

The midterms also will road-test messaging and agendas that will come into play in 2020. In Florida, the GOP gubernatorial nominee, Rep. Ron DeSantis, is an all-in Trump Republican — which is making establishment Republicans nervous. His Democratic opponent, Tallahassee’s liberal mayor, Andrew Gillum, upset more established Democrats. That contest will test boundaries for both parties.

If Republicans lose badly in November, could Trump face a primary challenge? He probably would weather it, but no incumbent president wants that problem. More critically, would a bad election for Republicans cause cracks in a coalition that has been surprisingly strong and consistent in its support for the president?

The outcomes in key states will be closely watched, especially those that were crucial to Trump’s election — a swath of states in the Midwest, and Florida — and some of those that Democrats would like to put into play in the future, Arizona and Georgia the most prominent.

Finally, as several strategists noted, a Democratic victory in 2018 would mark the fifth election in the past six — the others being 2008, 2010, 2014 and 2016 — that can be defined as change elections. If that’s the case, it will be another reminder of the power of change and the degree to which voters remain unhappy with the state of politics.