Georgia’s closely watched race between incumbent Democratic Sen. Raphael Warnock and Republican challenger Herschel Walker is likely headed to a runoff, according to a top official for the Georgia Secretary of State’s Office, which oversees elections.\n\nGabriel Sterling, the office’s chief operating officer, tweeted Wednesday morning that, “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.”\n\nAs of about 9 a.m. Wednesday, Mr. Warnock led Mr. Walker by about 30,000 votes out of 3.9 million cast—but he had under 50% of the vote, according to Georgia’s Secretary of State’s Office. A Libertarian candidate had about 2% of the vote. Under Georgia law, statewide candidates must win more than 50% of the vote or the two top vote-getters face each other in a runoff. The runoff would be held Dec. 6.\n\nFor months polls showed the race to close between Mr. Warnock, 53 years old, an Atlanta pastor, and Mr. Walker, 60, a former professional football player endorsed by former President Donald Trump.\n\nThe Georgia Senate race already is one of the most expensive congressional races of all time, with about $250 million spent on political ads by both parties. With a runoff, it will get even more expensive, with nonpartisan analysts saying it could become the most expensive congressional race ever.