Election Day guide: A rundown of what you need to know about the 2020 election

Thirty-five seats are up in this year’s election, including two with special elections. Democrats need a net gain of three seats if Joe Biden wins the White House and four if he doesn’t to take control of the Chamber. But when we know who won the Senate could be delayed, as both races in Georgia, as well as the less competitive ones in Mississippi and Louisiana, could end up going to runoffs. Democrats see a wider map than they did at the beginning of the year, though still not an easy path to gain what they need. Republicans are defending almost twice as many seats as Democrats this year. And it could take days, even more than a week, for the final results in Alaska, Maine and Montana to be counted if the races there are close. See a rundown of the races and the stakes.

The Democrats enter the night with a majority, and most watchers expect them to hold on to that, though some seats will swap control. Democrats are hoping to win over a few more suburban seats after picking up a lot of them in 2018, and Republicans are hoping to win in places won by Trump. Get a rundown of the races to watch here.

It’s not a big year in governor races. In Montana, Democratic Gov. Steve Bullock is term-limited and running for U.S. Senate, and it’s a toss-up on who will replace him. North Carolina Gov. Roy Cooper (D) got high marks for his handling of the coronavirus pandemic and is leading in polls. In New Hampshire, Republican Gov. Chris Sununu has consolidated support in a Democratic-leaning state. The only other one to watch is Missouri, where Republican incumbent Mike Parson is trying to hold off a challenge from Nicole Galloway, the state auditor. There are also states where control of state legislative chambers could flip; see where.

According to The Post’s average of national polls, Biden leads Trump by 10 percentage points nationally, 52 percent to 42 percent. Biden’s margin in the battleground states of Michigan and Wisconsin is nine points; it is five points in Pennsylvania, five in North Carolina, four in Arizona and three in Florida. Biden’s lead is bigger than Hillary Clinton’s was in 2016. But it’s good to remember that polls give us a rough estimate of a candidate’s support at a given time. They cannot predict who will win. Here’s how polls work, and how they’ve changed since 2016.