Here's a striking stat: The House of Representatives has flipped parties only three times in the past 60 years. The conventional wisdom in Washington right now is that Democrats are about to make it four.

As we come up on 100 days before the midterm elections, nearly every key sign is pointing to Democrats controlling the House of Representatives next year for the first time since 2010.

“Democrats remain substantial favorites for House control,” writes David Wasserman, a nonpartisan election analyst for the Cook Political Report, in an analysis out Friday that has the political world buzzing.

Of course, the conventional wisdom in Washington is fallible. (See: Trump vs. Clinton, 2016.) And next week we'll be analyzing why it might be wrong.

But while Republicans are publicly bullish they'll keep the House, nonpartisan analysts are leaning toward Democrats. That's because there are some solid reasons to predict that this time, Democrats will win. Let's run those down.

Retirements and the map: Even before election season got started, Republicans were vulnerable to a Democratic takeover. Democrats need a total of 23 pickups to take back the House, and there are 23 Republicans sitting in districts Hillary Clinton won.

Then Republicans started retiring in historic numbers. A notable number of House Republicans who have held their districts for years are leaving competitive districts in California, Pennsylvania and Florida. Since it’s much easier to win an open seat than to oust an incumbent, these races naturally get even more competitive for Democrats. Wasserman, of the Cook Political Report, found that for the past few decades, the party in power has always lost an open seat that its presidential candidate also lost in the election two years earlier.

With Democratic optimism on the rise for a "blue wave" in 2018, here's their strategy for winning more state and national seats than Republicans. (Joyce Koh/The Washington Post)

Republican operatives see November playing out much differently. “D.C. conventional wisdom predicted Hillary Clinton would be sitting in the Oval Office right now — instead she’s wandering around the woods of Chappaqua,” said Jesse Hunt, a spokesman for the National Republican Congressional Committee, in a statement to The Fix. “Our members and candidates are well positioned to prove the pundit class wrong once again.”

Energy on the left: Republicans argue that it's natural for the party out of power to perform well after a presidential election, so we shouldn't read too much into this stat. But Democrats are performing really well.

They've flipped 40 state legislature seats in special elections since Trump became president, including some deep in Trump country. This spring, they seized a congressional seat in Pennsylvania with Rep. Conor Lamb's win, also deep in Trump country. That prompted Democratic National Committee Chairman Tom Perez to confidently predict: “We can win everywhere.”

Democrats are performing better because more of their voters are voting. Turnout in Texas Democratic primaries this spring was nearly double what it was in the 2014 midterms, for example. That’s a trend playing out in primaries across the country right now.

Democrats have more candidates than they've ever had before. In state after state, Democrats boast of having candidates challenging nearly every incumbent Republican up for reelection in their state legislature or in Congress. That doesn't mean these candidates will all win — although Democratic strategists are genuinely excited about many recruits. (Republicans say they're happy with their candidates in competitive House races, too.)

But the point is that Democrats seem more motivated than they have before.

Take Texas again. Democrats there are running candidates in all 36 congressional races for the first time in 25 years. Politico reports on one manifestation of that: One of the most powerful Republicans in Congress, Rep. Pete Sessions (R-Tex.), is at risk of losing his seat to a well-funded Democratic challenger who has never held office before.

Democrats are doing well in polling: If you had to choose right now between electing a Democrat or a Republican to Congress, even if you didn't know their names or policies, whom would you choose? In polls over the past month that have asked this, voters say they would choose a generic Democrat over a generic Republican by an average of eight points, according to a Washington Post analysis of polling.

Election forecasters say Democrats need a six- to eight-point advantage in this kind of poll, called a generic ballot, to win a House majority. Democrats have consistently been ahead of that range.

Republicans are in power, with Trump at the wheel: Recent history shows that the party that controls the White House normally loses seats in Congress in the next election. But Republicans aren’t just in control of the White House. They’re in control of all of Congress. That allows Democrats to argue that whatever voters may not like about Washington is the other side's fault.

And Republicans don’t just have any president in the White House, they have one of the least traditional, most controversial and — over the past 18 months of his presidency — historically unpopular presidents in modern history. Democrats calculate that Trump will be a huge boon to them. They're trying to rally their base by underscoring Trump’s apparent deference to Russia, his short-lived policy of separating families at the border and his attempts to knock the knees out from under Obamacare.

But but but: There are two caveats to all this. Democratic voters traditionally aren’t as likely to vote in midterms as Republicans. Also, the economy is doing well (though it could slow), which is normally a major indicator of success for the party already in power.

All the other traditional signs that elections analysts use to predict performance favor Democrats this fall. Can the enthusiasm on the left, coupled with all the Republicans' struggles, be enough to lift Democrats to take back the House for the first time since 2010? Most people watching this think so.