With more than 99% of the vote counted, Warnock is narrowly leading against Walker, a former football star endorsed by former president Donald Trump.

However, Warnock has not yet reached the 50% threshold needed to avoid a runoff, according to data from Edison Research.

“While county officials are still doing the detailed work on counting the votes, we feel it is safe to say there will be a runoff for the US Senate here in Georgia slated for Dec 6,” Gabe Sterling, chief operating officer for Georgia secretary of state, said in a Twitter post today.

A third candidate, libertarian Chase Oliver, siphoned off 2% of the vote.

Warnock, a pastor at Ebenezer Baptist Church, the Atlanta church civil rights leader Martin Luther King Jr led, won his seat in a runoff in January 2021.

It was one of two Senate seats up for grabs in the formerly reliably Republican state.

In a political upset, both Democrats won their races, handing their party the barest of majorities in the chamber.

Those races were the most expensive congressional elections to date at that time, with the special election between Warnock and his Republican opponent, businesswoman Kelly Loeffler, drawing nearly US$363 million, according to Open Secrets.

So far, Warnock’s campaign has spent US$135.8 million, while Walker’s campaign has spent US$32.4 million, according to data from the Federal Election Commission.

Millions in outside spending are also expected to flood the state.