Georgia’s Senate race is heading to a runoff. Here’s how it will work.

ATLANTA — One of the most closely watched races in this year’s midterm elections is headed to a runoff after neither of the top two candidates vying for Georgia’s open Senate seat managed to secure a simple majority of votes, a requirement under state law for an outright victory.

After the midterm votes were counted, Sen. Raphael G. Warnock (D), who won his seat in a special election in a Jan. 5, 2021, runoff, had 49.4 percent, and his Republican rival, Herschel Walker, had 48.5 percent.

“There is one race in our state that is going to be moving to the December 6th runoff. That is the race for the United States Senate between Senator Raphael Warnock and Herschel Walker,” Georgia Secretary of State Brad Raffensperger said Nov. 9.

The contest has thrown Georgia’s election rules back into the national spotlight, after last year’s runoff election handed Democrats unified control of Washington and enabled them to pass much of President Biden’s agenda. Shortly after that, Gov. Brian Kemp (R) signed into law a major — and in some parts controversial — rewrite of the rules governing elections and voting in the state. That law changed the timeline and logistics of runoff contests. Here’s what to know.

A runoff election is a second election used to determine the winner of a race in which no candidate has earned more votes than the required threshold for outright victory. In most cases, the two candidates who won the most votes then go to a tiebreaking runoff contest.

Georgia is one of only two states — the other is Louisiana — where runoffs are required in general elections where no candidate has secured more than half of the votes. In most other states, a candidate wins a general election by securing the most votes — what is also called a plurality. Runoff elections are a legacy of Jim Crow-era politics crafted to ensure that White Southerners held unchecked power over Black Americans in the region.

Georgia requires anyone elected to public office in a general election to have secured a simple majority of votes, except for electors (who cast their votes in the electoral college) in presidential contests, meaning that close races for Congress may require a tiebreaking race.

In a runoff, the candidate with the most votes wins.

According to Georgia law, the two candidates in the runoff always should be the ones with the highest number of votes — so if a candidate drops out or otherwise can no longer stand, the candidate with the next-highest number of votes becomes eligible to be in the runoff.

If a write-in candidate is eligible for election in a runoff, that person’s name is added to the independent column of runoff ballots.

According to Georgia’s new voting law, runoffs should be held on the 28th day after an election is held — down from nine weeks for federal races. This means any runoff in Georgia’s Senate race would take place on Dec. 6 this year. The date can be changed only by a court.

The law also states that early voting should begin “as soon as possible” but no later than a week before the runoff. This would put the latest possible date for the start of early voting for the runoff at Nov. 28 (voting began on Nov. 26).

Proponents of the change argued that “the lengthy nine-week runoffs in 2020 were exhausting for candidates, donors, and 120 electors.” But the shortened time frame between an election and a runoff has come under fire from some voting rights advocates, who say it does not leave voters enough time to apply for mail ballots and cast their votes early. The law also “eliminates the window for voter registration to reopen for federal elections,” according to the American Civil Liberties Union of Georgia, meaning it would not be possible to register new voters in time for the runoff.

All registered voters in Georgia can cast their ballots in a runoff election; to be eligible to vote in this year’s runoff, they must have registered to vote by Nov. 7.

The short time frame between an election and a runoff means there is not enough time to send military and overseas voters another round of ballots; instead, they will be sent a special absentee runoff ballot along with their regular absentee ballot before the primary or general election takes place. The runoff ballot will give these voters the option to rank their choice among all possible candidates for each office, and that ballot will be used in the case of a runoff.

Annabelle Timsit reported from London.

This story has been updated since it first published.