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

Michigan gave Biden his highest margin of the three northern battleground states in 2020, but the race was still close, and it looks even tighter this year, with Harris only marginally ahead in 538's final forecast of the state.

Black and Arab Americans will play a key role in either candidate's victory. Polls have shown Black voters, who make up 13% of Michigan's electorate, swinging toward Republicans this year, though how big that shift will be remains to be determined. Michigan also has the largest share of Arab Americans in the country — a community that has been rocked by the wars in Israel, Gaza and Lebanon. Polling among the demographic — which makes up around 4% of the state's population — is limited, but the data we do have shows a major decline in support for Democrats following heavy protests over the Biden administration's response to the conflicts. Any loss of support for Democrats among these key groups could have major implications for which party ends up winning the state's 15 electoral votes.

There are also several key downballot races to watch in the Great Lakes State. Democratic Rep. Elissa Slotkin is favored to win the state's open U.S. Senate seat (currently held by retiring Democratic Sen. Debbie Stabenow) over former GOP Rep. Mike Rogers. Slotkin wins 76 in 100 times in 538's final forecast of the race — a clear advantage, but one that still leaves open the very real possibility of a Rogers win.

Michigan is playing host to multiple key U.S. House races too; the state's 7th, 8th and 10th districts are rated as competitive, though Democrats have an edge in the 7th, while Republicans are slightly favored in the 8th and 10th. Incumbent Democratic Rep. Hillary Scholten has a comfortable lead in the 3rd District, though the race could still be competitive if the GOP is having a great night. The race for the state House is a nail-biter, though, with Democrats fighting to hold on to the narrow majority they won in 2022 and the state government trifecta they secured with that win two years ago.

Biden has been slammed by voters' pessimism over the economy since he took office. Some of that was the result of an economy scrambled by the COVID-19 pandemic, but Americans continued to feel negative about it even as some indicators picked up. A 538 analysis in June found that even which economic indicators voters cared most about were changed by the experience of the pandemic and the lockdowns and recession that came with it. While Biden was the presumptive nominee, Trump maintained a big advantage on the economy with voters.

When we spoke to voters about the economy in May, partnering with the nonpartisan research firm PerryUndem for two separate focus groups with Trump-leaning voters and Biden-leaning voters, the voters felt in general that the cost of living had been better four years ago. That was true for purchases as small as eggs at the grocery store, and as big as housing or college tuition. In general, Biden leaners planned to vote for the president despite the economy because they agreed with him on other issues or disliked Trump, while Trump-leaning voters were voting for him in large part because of the economy, naming proposals like his calls to drill for more domestic oil and to prioritize hiring American workers first.

So a big question for Harris' campaign is whether it's done enough to escape the economic albatross that Biden couldn't seem to shake. The economy remains a top issue for voters, but it does look like Harris is performing better than Biden did. Since entering the race in July, she has worked to reframe the issue around affordability, and championed policies like helping families by homes, and the New York Times/Sienna College poll from Oct. 20-23 found that Harris had cut Trump's lead on the issue to 6 points, compared to 13 points in early September.

While congressional redistricting typically only happens every 10 years, coinciding with the U.S. Census, five states nevertheless changed their congressional district lines since the 2022 midterm elections due to court-ordered redistricting. These changes can greatly impact the race for control of Congress, since even small shifts in district lines can change the partisan lean of those seats in big ways. Move a boundary a little bit here and a little bit there, and all of a sudden a district that was solidly Republican is now a toss-up (or the other way around). This is even more true in cases where a state's map saw more radical alterations.

In three states, redistricting was mandated under the Voting Rights Act, which in some cases requires the creation of majority-minority districts. Alabama and Louisiana each saw their congressional maps struck down and redrawn to include an additional majority-Black seat, both of which are likely pickups for Democrats. In Georgia, despite redistricting that boosted the number of Black voters in an Atlanta-area district, the new map isn't likely to result in any changes to the state's congressional delegation.

In North Carolina and New York, state supreme courts overturned prior maps as unconstitutional and allowed their state legislatures to redraw the lines to be more favorable to one party or the other. While North Carolina's state legislature aggressively gerrymandered their new map in favor of Republicans, New York's state legislature left their lines mostly unchanged, making tweaks that only minorly benefit Democrats.

All told, Republicans stand to pick up three to four seats in North Carolina thanks to redistricting, while Democrats look positioned to grab two across Alabama and Louisiana. The smaller changes in New York could also help Democrats in a number of competitive races there. Given the tight margins in the current Congress, control of the House of Representatives could ultimately come down to the changes to these states' congressional maps.

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.