Election 2024 updates: With Arizona, Trump sweeps all 7 swing states

The race for control of the House is on a knife's edge. With Republicans currently holding just a 221-to-214 majority (grouping vacant seats with their previous party), Democrats need only a four-seat net change in their favor to regain a one-seat edge in the House.

Given those narrow margins and the broader competitive political environment, 538's forecast of the House understandably gives each party just about a 1-in-2 shot of controlling the chamber after the 2024 election — making the race a true coin flip. Much like the presidential contest, the outcome here is very uncertain.

Digging into individual races, most seats in the House are uncompetitive, so the contests that will decide the House majority make up a very small proportion of the overall map. In 378 of the chamber's 435 seats, one party or the other has a better than 95-in-100 shot of winning, per the 538 forecast. Yet even among the 57 potentially competitive seats left, only some of those are likely to be that competitive, with the forecast viewing most as likely to go to one party or the other.

Ultimately, the universe of seats that will play the largest role in determining which party wins a majority includes 23 seats. In each of these contests, neither side has better than a 75-in-100 chance of victory — the forecast views each as a toss-up or as leaning only slightly toward one party or the other.

Republicans find themselves defending more of this battleground turf than the Democrats do, which is unsurprising given that they flipped a number of these seats in the 2022 midterm elections — nine of the 15 GOP-held seats on this list have incumbents first elected that year. Many of the most competitive seats the GOP is defending are also in "crossover" districts, where the party that holds the seat is different from the one that would have carried it in the 2020 presidential election. While 2020's presidential results of course may not be fully predictive of what we'll see in 2024, crossover districts matter because a seat's presidential vote is a strong baseline indicator of which direction the district is likely to lean, especially nowadays given our sharply polarized politics. Few House members win elections in districts that their presidential nominee didn't also carry in the same election cycle, with the total hitting a recent low of 16 seats in 2020 — just 4% of all 435 districts.

The 2018 cycle was a watershed year for Democratic women, who outperformed Democratic men in their primaries. And in November of that cycle, female candidates put a nail in the "women aren't electable" coffin when they were responsible for more than 60% of the congressional seats that flipped from red to blue.

In congressional races today, a number of Democratic women are challenging incumbent Republicans in seats our forecast rates as competitive, and Democrats are hoping for a similar outcome as 2018. This includes Sue Altman in New Jersey's 7th District, who is challenging Rep. Thomas Kean Jr., and Janelle Bynum in Oregon's 5th District, who is challenging Rep. Lori Chavez-DeRemer, one of just 34 Republican women currently in the House. (If Bynum wins, she will be the first Black person to represent Oregon in Congress.) In Arizona's 6th District, Kirsten Engel is challenging Rep. Juan Ciscomani.

GOP women also have a recent track record of flipping seats: In 2020, Republicans recruited women to run against vulnerable Democrats, in a strategy to flip highly competitive House districts, and many of them did defeat Democratic incumbents. There are a couple of Republican women challenging incumbents in races that our forecast suggests could be close, like Laurie Buckhout in North Carolina's 1st District, who is challenging Rep. Donald Davis, and Yvette Herrell in New Mexico's 2nd District, who is challenging Rep. Gabriel Vasquez. Buckhout and Herrell are both running in races our forecast rates "Likely Democrat," but they are still competitive.

If these Democratic and Republican women win, it could certainly add to the number of women in Congress. However, plenty of incumbent women who represent purple districts are facing challenges of their own, like Democratic Reps. Emilia Sykes in Ohio's 13th District, Marie Gluesenkamp-Perez in Washington's 3rd, Susan Wild in Pennsylvania's 7th, and Yadira Caraveo in Colorado's 8th. Republican women at risk of losing their seats include Michelle Steel in California's 45th and Chavez-DeRemer.

At stake is not just these seats, but gender diversity in Congress, which remains low. After the 2022 election, women made up just 29% of the House and 25% of the Senate. But the partisan gap is especially stark: Democratic women make up 41% and Republican women make up just 16% of their respective parties' members of Congress.

I'll be watching these races today, to get a sense of whether either party will add more women to their caucus, and if the progress women have made over the last several cycles (especially since 2018) will finally stall.

I wish I could tell you something more helpful than "it's close," folks, but according to 538's final presidential election polling averages, that really is the most responsible conclusion.

According to 538's average of national polls, Vice President Kamala Harris currently has a 1.2 percentage point lead over former President Donald Trump in the national popular vote. Harris, at 48.0% of the vote in our average, is polling about 0.6 percentage points below her peak on Oct. 1 this year. Trump, meanwhile, posted his highest vote share of the campaign today, at 46.8%. That is the same exact % of the vote he won in 2020, to the first decimal point.

The picture is not much different at the state level. According to our final polling averages, the margin between Trump and Harris is 2.1 percentage points or fewer in all seven swing states. Trump currently leads by 2.1 points in Arizona, 0.9 points in North Carolina, 0.8 points in Georgia and 0.3 points in Nevada. Harris is up by 1.0 point in Wisconsin and in Michigan. And in Pennsylvania (the state that's most likely to decide the outcome of the election), Harris has a tiny 0.2-point edge.

Of course, it is worth stressing that the polls will not be exactly correct. In fact, they very likely will not be. Polls overestimated Democrats by more than 2 points in both 2016 and 2020, for example, and underestimated Republicans by 2 points in a handful of key Senate races in 2022. Errors that large could cause the entire Electoral College picture to flip. And in fact, the bias in polls was nearly twice as high — 4 points — in the 2020 race. Our election model thinks the expected bias in polls this year is 3.8 percentage points on average, and could be more or less, favoring either party equally. When we did the math we found that polling error can be expected to be larger than 2 points toward either candidate about 60% of the time.

One of the trends we are going to be watching after Election Day is how educational polarization might have intensified among the American electorate. The Republican Party currently holds a six-point lead over the Democratic Party in voter preference among registered voters without a college degree, while the Democrats have a 13-point advantage among those with at least a bachelor's degree, according to Pew Research. This is a marked reversal from dominant voting patterns not even 20 years ago, when Republicans were predominantly viewed as the party of the wealthy and Democrats the party of the working class.

This divide has fundamentally reshaped our politics in recent years. Think of the Republican Party's embrace of anti-expert views on topics like vaccination or climate change or the wider conflict over teaching about race and gender in schools. These culture war issues — which also stem from a growing diploma divide, where higher educational attainment is increasingly aligned with liberal political values — have changed what issues our political parties prioritize, how they operate and which voters they try to win.

Recently, the 538 Politics podcast interviewed Matt Grossman and David Hopkins, political scientists and authors of "Polarized by Degrees: How the Diploma Divide and the Culture War Transformed American Politics." To hear their takes on this trend, check out the podcast here.