For Democrats, the prospect of further retirements and revived GOP infighting has sparked talk of competing for Senate seats previously thought out of play. That is particularly true with candidates like Moore, long considered a fringe political figure who has, among other things, expressed doubts about whether former president Barack Obama was born in the United States and referred this month to “reds and yellows” in remarks on race. On the eve of the election, Moore, wearing a white cowboy hat and a black leather vest, pulled a handgun out of his pocket and flashed it at a rally.

“It’s an acid flashback to 2010,” said Charlie Sykes, a former conservative talk-radio host, referring to the year when seasoned GOP figures lost Senate primaries across the country as incendiary conservatives charged forward.

“It’s almost as if there is a compulsion in the party to nominate the most ‘out there’ candidate just to show you can, with no concern about what that means for the rest of the party,” Sykes said. “Republicans — and that means Trump, too — have unleashed something they can’t control.”