WASHINGTON (AP) — Thirty-five U.S. Senate seats are on the ballot Tuesday, which will determine control of the legislative chamber for the next two years.

But due to election law quirks in the states of Georgia and Louisiana, where a total of three seats are up for grabs, it is possible that the fate of the current 53-47 Republican majority will remain unknown for weeks to come.

Both states require a Senate candidate to capture over 50 percent of the vote in order to win outright on Nov. 3. If not, the top two vote-getters move on to a runoff election, which Louisiana will hold Dec. 5 and Georgia has scheduled for Jan. 5.

WHAT'S AT PLAY

Louisiana is solidly Republican and Sen. Bill Cassidy is widely expected to win reelection, even if he's forced into a runoff by a field of 14 other contenders.

But Georgia, where there are two competitive races, could ultimately determine which party is in the majority if Republicans do well in other Senate battlegrounds.

In one of the Georgia races, Republican Sen. David Perdue is locked in a tight contest with Democrat Jon Ossoff. Libertarian Shane Hazel will also be on the ballot.

The other is a special election that will decide who completes the remaining two years of retired Republican Sen. Johnny Isakson’s term.

Under Georgia law, there was no special election primary to winnow the field. Instead, a jumble of 21 candidates will appear on the ballot. They include Republican Sen. Kelly Loeffler, who was appointed to temporarily hold the seat until the election; GOP U.S. Rep. Doug Collins, a Trump ally; Democrat Raphael Warnock, a pastor at Ebenezer Baptist Church, where Martin Luther King Jr. once preached; and Democrat Matt Lieberman, the son of former Sen. Joe Lieberman.

The race will likely to go to a runoff unless Warnock, a leading contender in recent polls, garners just over 50 percent of the vote.

WHAT IT MEANS FOR THE PRESIDENT

Control of the Senate has wide-ranging implications for whoever is elected to the White House.

If Democratic nominee Joe Biden wins, the outcome of Senate races will determine whether he is able to enact an ambitious liberal agenda — or face Republican gridlock. Democrats already control the House, which they are expected to keep.

If Trump wins, he will look to the Senate to confirm key nominees, like federal judges, and serve as a bulwark against Democrats in the House.

But who holds the presidency could also play a role in determining the Senate majority: In the case of a 50-50 split, the vice president can cast tie-breaking votes.