Updated at 11:40 a.m. ET Tuesday
The political world has trained its focus on Georgia's two U.S. Senate races, which will settle the kind of Senate that President-elect Joe Biden will be dealing with.
The races, taking place Tuesday — the day before Biden is slated to be certified by Congress as the winner of the 2020 presidential election — are expected to be close. Consider that Biden won the rapidly changing but previously traditionally Republican state by fewer than 12,000 votes.
Two wins for Democrats, and they will control the Senate, along with the White House and the House, in a few weeks — a stark turnabout from the beginning of the Trump presidency four years earlier, when Republicans had full control.
But one Republican win, and it's split government, with the GOP likely able to block most of Biden's legislative agenda. That's why, between the candidates and outside groups, almost $500 million has been spent on ads for the races in just about two months.
It's notable that these contests are the first since the 2020 presidential election and that the usual metrics to measure races are mostly being cast aside. Polling was off in measuring Republican support for President Trump in the 2020 election, so polls are being looked at skeptically. And money didn't matter everywhere in 2020 — some candidates raised more money and lost badly, while others won.
Trump has also thrown a big variable into the elections with his mixed messages on voting. On the one hand, he's casting doubt on voting by baselessly claiming elections are rigged — and blaming Georgia's secretary of state for reducing GOP enthusiasm. On the other, he's encouraging Republicans to turn out and vote.
Everyone is flying a little blind heading into Tuesday, but here's what you need to know:
One contest pits incumbent Republican Sen. David Perdue against Democratic challenger Jon Ossoff. Perdue was first elected in 2014 and is seeking reelection.
The other race features incumbent Republican Sen. Kelly Loeffler against Democrat Raphael Warnock, senior pastor at Ebenezer Baptist Church in Atlanta. Loeffler was appointed to her seat in 2019 after former Republican Sen. Johnny Isakson retired because of health reasons.
Why are these elections so important?
In determining control of the Senate, the results will put one party or the other in charge of the legislative agenda. A Democratic sweep would result in a 50-50 Senate with soon-to-be Vice President Kamala Harris being the tiebreaking vote in the chamber.
While there still is a 60-vote threshold to get legislation through, it would be much easier to confirm Biden's Cabinet picks and judicial appointments than if Democrats were in the minority.
Democratic leader Chuck Schumer, who would be presumed to be Senate majority leader if Democrats took control of the chamber, would be in charge of what goes to the floor, including, if it came to it, items like doing away with the filibuster entirely or adding justices to the Supreme Court.
If Republicans won, though, GOP leader Mitch McConnell would be able to largely thwart much of Biden's agenda.
Why are the elections taking place now?
These are runoffs. Georgia does things a little differently than most other states. Back in November, if one of the Senate candidates had gotten 50% plus one vote, that candidate would have won the election outright and the state would have avoided a runoff in that race. But that didn't happen in either contest.
Perdue came closest — he won 49.7% of the vote to Ossoff's 47.9%. Calculated another way, out of almost 5 million votes cast, Perdue missed avoiding a runoff by a little over 13,000 votes.
The Loeffler-Warnock race had another hurdle. Because it was a special election, there weren't primaries and everyone ran on the same ballot together at once.
In a field of 20 candidates, including a prominent Republican challenger, Loeffler got just over a quarter of the vote.
Warnock actually finished ahead of her, with about a third of the vote. But when the votes were combined by party in that race, Republicans were narrowly ahead of Democrats, 49.4% to 48.4%.
Interest is high, given not just the money spent, but the high early-vote turnout, which began Dec. 14 and continued through Friday.
What does the early voting tell us?
It's always a little tricky to interpret early-voting data and ascribe real meaning to it, but Democrats see some hopeful signs.
Three million people cast ballots early. That's a record already for total votes cast in a Georgia runoff election. And who is voting is what's giving Democrats optimism: Black voters are making up a higher percentage of voters than they did for the Senate races in November, and turnout in Democratic congressional districts is higher than in GOP-held ones.
Of course, Democrats saw hope in early-voting numbers in Texas before Nov. 3, and Trump wound up winning that state by 6 points, a wider margin than the polls had predicted.
How much money has been spent on the races?
Almost $500 million has been spent on advertising between the two races in just the two months since the presidential election, according to the latest numbers provided to NPR by AdImpact, a political ad-tracking firm. The figures measure ad reservations between Nov. 4 and Jan. 5.
With outside groups included, Republicans have outspent Democrats $271 million to $218 million.
Ossoff's and Warnock's campaigns have both outspent Perdue's and Loeffler's by a combined $160.1 million to $99.8 million. Ossoff's campaign has spent the most of the campaigns, at $87.6 million, followed by Warnock at $72.5 million, Perdue at $50 million and Loeffler at $49.8 million.
But Republican outside groups have more than made up the difference, outspending Democrats almost 3-to-1, $171.2 million to $58 million.
One Republican hardly spending on Georgia, however: Trump. Despite desperate fundraising pleas ("I need YOU to secure a WIN in Georgia," and "Help us WIN both Senate races in Georgia & STOP Socialist Dems"), most of the money raised from those pitches is being pocketed by Trump's PAC, Save America.
When do polling places open and close?
Polls open at 7 a.m. ET and close at 7 p.m. ET on Tuesday. Voters who are in line by 7 p.m. ET are allowed to vote.
A previous version of this story incorrectly said that in both Senate races, all candidates from all parties were on one ballot in November. That was only true of the special election, which ended in a runoff between Sen. Kelly Loeffler and Raphael Warnock. The Perdue-Ossoff contest went through a traditional primary process.