ATLANTA (AP) — Candidates for one of two U.S. Senate seats still hanging in the balance will face off in a debate that is drawing strong interest beyond Georgia.

That is because the seat — now held by incumbent Republican Kelly Loeffler and being challenged by Democrat Raphael Warnock — is one of two that will tip control of the Senate to either Republicans or Democrats. Loeffler and Warnock face off Sunday in a debate sponsored by the Atlanta Press Club. Although Warnock has sought additional debates, none have been scheduled yet, meaning this could be the only head-to-head debate between the two candidates.

The other Senate seat still undecided is between Georgia Republican U.S. Sen David Perdue, who has declined to meet Democratic challenger Jon Ossoff in additional debates after the two jousted twice before the general election. Ossoff will get a solo platform Sunday to make his case.

The runoffs will determine which party controls the U.S. Senate, prompting a huge wave of money and organizing effort trying to get Georgians to vote again on or before Jan. 5. The state's voters cast a narrow majority of ballots for Democrat Joe Biden in November, but Perdue outran President Donald Trump while Ossoff trailed Biden.

Republicans currently hold a 50-48 edge in the Senate, but if Democrats win both races, Vice President Kamala Harris would cast the tiebreaking vote in the incoming Joe Biden administration, giving Democrats control. Republicans will retain their current majority even if they win only one of the two races.

In both races, a runoff is required under Georgia state law because no candidate reached 50% in November. Perdue fell just short of defeating Ossoff because a Libertarian candidate won a small slice of the vote, while Warnock led Loeffler in a 20-way field in which no candidate came close to 50%.

The Republicans are attacking their Democratic opponents as socialists and radicals, saying giving control to the party would lead to unacceptable consequences. Democrats are attacking the stock trading activity of Perdue and Loeffler, saying it proves the two are rich people who care more for their own pocketbooks than for people suffering from the COVID-19 pandemic.

Loeffler and Perdue rallied Saturday in Valdosta with Trump, who came to the state to support the candidates despite continuing questions over whether Trump's unproven attacks on Georgia's presidential balloting will cause some of his Republican supporters to shy away from voting in the runoffs.

Georgia Secretary of State Brad Raffensperger continued to defend the integrity of the presidential election Sunday. As a Republican, Raffensperger said on ABC's “This Week” that he wants Loeffler and Perdue to do well even though they both called for him to be removed from office, echoing Trump.

“These distractions, this disunity, it does make it more difficult,” Raffensperger said.

Loeffler and Perdue rallied Friday in Savannah with Vice President Mike Pence.

Warnock and Ossoff held a virtual rally Friday with former President Barack Obama.