LOS ANGELES — Candidate debates are usually routine events on the political calendar. But not in California’s U.S. Senate contest.

The two Democrats seeking the seat — state Attorney General Kamala Harris and U.S. Rep. Loretta Sanchez — have been unable to agree how many there should be, or when and where to hold them.

After weeks of squabbling, it’s possible a debate will never take place.

On Tuesday, Sanchez proposed a series of four debates, after Harris earlier agreed to two, one in Sacramento and one in Los Angeles.

That led to another stalemate.

“Our campaign is done debating debates,” Harris strategist Sean Clegg said in an email, rejecting Sanchez’s plan for additional face-offs.

Sanchez spokesman Luis Vizcaino said Harris’ rejection of the congresswoman’s four-debate schedule “is closing the door to California voters.”

Meanwhile, time is running short. Mail-in ballots will begin arriving at homes in about a month, meaning voters could be making decisions without ever seeing the candidates on the same stage.

The race to replace retiring Sen. Barbara Boxer was expected to be a barrier-shattering brawl, with historic overtones. Sanchez, if elected, could become one of the first Latinas to hold a U.S. Senate seat. Harris could become the first Indian woman and the second black woman elected to the Senate. Illinois Sen. Carol Moseley Braun was elected in 1992 and served one term.

But the contest has been mostly low-key and overshadowed by the presidential race.

Sanchez has been lagging in polls and fundraising for months, and her push for more debates is not surprising. With a tight budget for advertising, televised debates could be her best opportunity to slow Harris’ momentum.