Republicans have a slim, three-seat majority in the Senate that they’re trying to hold on to in November. And they are in for a battle to do it: There are 13 chances on this list for Democrats to flip Senate seats and just two for Republicans.

But Republican strategists say they’re seeing evidence that Republican-leaning voters turned off by President Trump’s handling of the coronavirus are starting to come home to the party in the final stretch, and they think it might be enough for some of these vulnerable Republican senators to hang on and deny Democrats the majority.

Democrats’ path to the majority is to net at least four Senate seats or net three and win the White House to get the majority, but that requires going through some Republican-leaning states.

For now, the most competitive races remain largely unchanged from our last rankings in August. We’ll update these rankings again between now and November.

Because so many of the races could go either way — while others are more of a stretch — we divided them in three categories: More likely to flip than not, toss-ups, and could flip under the right conditions.

More likely to flip than not: Alabama, Colorado and Arizona

1. Alabama (Democrat-held): Sen. Doug Jones (D) remains the most vulnerable senator in 2020. He’s facing former Auburn University coach Tommy Tuberville, a first-time candidate that Democrats are modestly optimistic could stumble in the spotlight. But no one with a stake is arguing that a Senate race in one of the most pro-Trump states in the country is a toss-up.

2. Colorado (Republican-held): Sen. Cory Gardner (R) is trying to pull away from Trump in this purple-blue state by talking about an outdoors conservation bill he wrote, rather than how he voted to acquit the president on impeachment. His opponent, former governor John Hickenlooper (D), hasn’t seen an ethics scandal hit his polling in a significant way. A new AARP poll of all likely voters shows Hickenlooper leading 51 percent to Gardner’s 46 percent. Gardner will need Trump to perform better than expected here to keep this seat. Said one Republican strategist: “If the president is really struggling in Colorado, that makes the math difficult for Cory.”

3. Arizona (Republican-held): Former astronaut and gun-control activist Mark Kelly is one of the Democrats’ strongest candidates of 2020. He has outraised Sen. Martha McSally (R) the entire race and is leading in recent major polls. Republicans are hopeful this could become more of a toss-up race, because Arizona is a Republican-leaning state. It hasn’t voted for a Democrat for president in decades, and Kelly would also be just the second Democratic senator from this state in 25 years. (Democratic Sen. Kyrsten Sinema beat McSally in 2018.) A new CBS/YouGov poll in Arizona finds Kelly leading by seven percentage points.

Toss-ups: North Carolina, Maine, Iowa, Georgia, Montana

4. North Carolina (Republican-held): The political consensus is that Sen. Thom Tillis (R) is the underdog to hold on to this seat. He narrowly won his first term six years ago and is running in a state in which Democrats have since made major gains. North Carolina also may be the swingiest state at the presidential level, which could propel Democrats to get out and vote in higher numbers than they normally do. Both a Monmouth University and Fox News poll released in early September give Cal Cunningham an edge, and a CNN poll out Tuesday shows it basically tied: 47 percent of likely voters say they back Cunningham, over 46 percent backing Tillis.

5. Maine (Republican-held): One Democratic strategist predicted the battle for the majority could come down to these next two races. Maine and Iowa are going to be down to the wire, but as the home stretch to the election begins, Republicans say they feel good about where they are in both.

In Maine, Sen. Susan Collins (R) is trying to lean on her expertise and history representing the state for more than 20 years to overcome Democratic attacks, led by her opponent, Maine’s House Speaker Sara Gideon (D), that she is no longer independent from Trump. (Maine is not a state Trump is expected to win.) Collins was also a co-author of the small-business loan program when the coronavirus shut down the economy, which Republicans say can help buoy her. A new Quinnipiac University poll that was released after this story published has Gideon leading Collins 54 percent to 42 percent — and Collins more disliked than liked by voters in her state. As another Democratic strategist put it: “It takes a perfect storm to unseat someone like Collins, but that storm is happening.”

6. Iowa (Republican-held): We moved Sen. Joni Ernst’s (R) reelection to the toss-up category this summer, and it certainly deserves to stay there. Democrats now have a voter registration advantage over Republicans in the state, which one Democrat joked may be the only good thing to come out of the disastrous Iowa presidential caucuses in February. Iowa is among the reddest states in this toss-up category — Trump won it by nearly 10 percentage points in 2016 — and a new AARP poll of likely voters shows Ernst ahead at 50 percent over Democratic challenger Theresa Greenfield at 45 percent. But polls from this summer showed Trump only narrowly leading Democrat Joe Biden. Senate Democrats’ campaign arm doubled its investment here. This race may come down to whether Greenfield has enough crossover appeal to rural, more Trump-leaning voters.

7. Georgia (Republican-held): The final three toss-up races are more of a stretch for Democrats, but they’ll need at least one of them if they fall short in the states above. Trying to unseat Sen. David Perdue (R) is within the realm of possibility for Democrats, because Georgia is shaping up to be competitive at the presidential level. Both sides are spending tens of millions of dollars here. Republicans are trying to frame Democratic challenger Jon Ossoff as too liberal for the state, and Democrats are trying to frame Perdue as a political insider gaming the system for his own benefit. Democrats think Perdue may be caught off-guard by the rapid diversification of Atlanta’s suburbs. A new AARP poll has the race basically tied, Ossoff at 48 percent and Perdue at 47 percent. Both sides think this could go to a runoff, which happens per Georgia election rules if no one gets to 50 percent. That potentially pushes the fate of the Senate majority to January.

8. Montana (Republican-held): It’s a sign of Trump’s weakness over the coronavirus that Montana is on here. It’s a state he won by 20 points in 2016, but that year, Democratic Gov. Steve Bullock also won reelection. Bullock was term-limited but will try to unseat Sen. Steve Daines (R). Like many governors, Bullock’s stock has risen as he handles the pandemic. But Republicans are trying to turn that into a weakness, with a GOP super PAC running ads on various controversies about the state’s response and its leaders. Senate Democrats’ campaign arm sees Montana as particularly competitive and has more than tripled its investment here. An AARP poll shows Daines leads Bullock slightly, 50 percent to 47 percent, and having him at 50 percent is an encouraging sign for Republicans that he can hang on.

Could flip under the right conditions: Georgia, Michigan, South Carolina, Texas, Kansas, Kentucky, Alaska

9. Georgia’s special election (Republican-held): This special election for a full term to the seat that appointee Sen. Kelly Loeffler (R) now holds is structurally more difficult for Democrats than the other Georgia race. That’s because it’s a jungle primary in which several candidates from both parties are on the ballot, and if no one gets 50 percent (they won’t), the top two vote-earners go to a January runoff. Democrats are optimistic that their top candidate, pastor Raphael Warnock, will make it to the top two, even if polling doesn’t bear that out yet. He’ll have to top a Republican challenger, Rep. Douglas A. Collins. There are other candidates in the race splintering the vote, but right now an AARP poll has Loeffler at 24 percent, Collins at 20 percent and Warnock at 19 percent. Democrats haven’t had luck in January runoffs in Georgia — and there won’t be a presidential race to help them bring out the vote.

10. Michigan (Democrat-held): Besides Alabama, this is Republicans’ only other pickup opportunity to offset any losses from the races above. It continues to look like a reach for them. Republican challenger John James, a conservative media darling, continues to outraise Sen. Gary Peters (D). But Biden is leading the state by an average of eight percentage points in high-quality polls, and Republicans acknowledge that they need that race to get closer for James to have a shot.

11. South Carolina (Republican-held): Democrat Jaime Harrison is raising an insane amount of money and giving Sen. Lindsey O. Graham (R), an unapologetic Trump ally, one of his toughest reelection fights ever. Harrison is doing well with moderate, independent White voters in the changing suburbs that gave House Democrats a big House win last year. They also say Harrison, who is Black, is rallying Black voters. A stunning Quinnipiac University poll in August had the race tied at 44 percent, drawing even more Democratic attention and money here. A new Quinnipiac Univerity poll out Wednesday, shortly after this story published, has them tied among likely voters at 48 percent. But there just may not be enough Democratic-leaning voters in South Carolina to help Harrison win.

12. Texas (Republican-held): Every cycle now, Democrats are focused on trying to turn Texas blue statewide, especially after a close 2018 Senate race. This time they have former congressional candidate and Air Force veteran MJ Hegar trying to take out Sen. John Cornyn (R). But Texas is a big, expensive state to advertise in, and Democrats have so many options elsewhere that they may not be able to make this as competitive as they wish. Polls show Cornyn with a lead. Though at the presidential level, polls show a dead heat there between Trump and Biden.

13. Kansas (Republican-held): This is the only new state on the list. Even though Republicans got the candidate they wanted through a competitive primary in August, Rep. Roger Marshall, Democrats think he’s a weak candidate as he questions public health advice on the coronavirus. This is a state that elected a Democratic governor in 2018 (against a flawed Republican). And a Republican super PAC raised eyebrows last week when it announced it was spending several million dollars to boost Marshall. Republicans say that’s a safety measure, given that Democrat Barbara Bollier had no major primary and has been on TV for a while defining herself.

14. Kentucky (Republican-held): We remain skeptical that Democrat Amy McGrath can unseat Senate Majority Leader Mitch McConnell (R-Ky.), despite her massive fundraising. She has struggled trying not to alienate Trump voters, and she had a stronger-than-expected primary challenger in the summer. Plus, McConnell’s priority is keeping the Senate majority, and that starts with his own race in a state he knows how to win. But Trump isn’t helping him. As the president’s numbers sink even in Kentucky, a Quinnipiac University poll from August had McConnell with a five-point lead over McGrath, which is narrower than some expected, and showed independents in Kentucky backing McGrath. It will still take a historic Democratic tsunami to knock out McConnell. Another Quinnipiac poll published after this story shows McConnell with a solid 12 point lead over McGrath among likely voters.

15. Alaska (Republican-held): Democrats are throwing their support behind independent Al Gross, a doctor and fisherman with money of his own to spend as he tries to unseat Sen. Dan Sullivan (R), who narrowly beat a well-known Democrat six years ago. Yet again, Trump’s handling of the coronavirus is the top reason it has the potential to be competitive. Alaska does have an independent streak and has elected Democrats to the Senate. But this state is also hard to poll, and some Democrats say they’ll need extra magic to get this in the win column.

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Democrats regained control of the House following the 2018 midterm elections. Can they hold their majority, and perhaps increase their seat count in 2020? (The Washington Post)

This post has been updated with newly released polling.