How the Shooting of Breonna Taylor Changed the Kentucky Senate Race

Jimmi Nicholson, who also works at the university, said that she was supporting Mr. Booker but that he probably could not win the general election because “it’s Kentucky and he’s an African-American male.”

Last year, though, Kentuckians overwhelmingly elected a black man to statewide office, installing a conservative McConnell protégé, Daniel Cameron, as attorney general. Kentucky Democrats have never nominated an African-American candidate to statewide office.

Joni Jenkins, the state House minority leader and a Booker supporter, said that Mr. Booker’s authenticity was more important than his race.

“Some of us elected officials run not to lose and play the safe game, but there ain’t nothing safe about Charles Booker’s campaign,” Ms. Jenkins said.

That, of course, is what worries leaders like Mr. Schumer, who Mr. Booker said has not reached out to him.

The Senate Democratic leader repeatedly pressed some prominent Kentucky Democrats to help him squelch a primary challenge to Ms. McGrath, admitting privately that she would not be a top-tier candidate, but that they could use her to raise money against Mr. McConnell and keep him pinned down in his own race, according to officials familiar with the conversations.

Speaking to reporters on Tuesday, Mr. Schumer expressed confidence in Ms. McGrath, but also nodded at how pleased he was that the race was diverting G.O.P. resources. “The Republican super PAC put $10 million into Kentucky,” he said, alluding to the Senate Leadership Fund.

Ms. McGrath may still hang on. It was not difficult to find voters who had already cast their absentee ballots for her. And to protect people from the coronavirus, Mr. Booker’s hometown, Louisville, will only have one polling place on Tuesday.