Mayor Karen Bass of Los Angeles claimed one of two spots on the November ballot late Tuesday, according to The Associated Press. Nithya Raman, a progressive former ally of the mayor, and Spencer Pratt, a onetime reality television star, were battling for second place.

Ms. Bass, 72, a former Democratic congresswoman, could avoid a November runoff and win another term outright if she receives more than 50 percent of the vote, but that scenario appeared unlikely after a fierce three-way contest in a field of more than a dozen contenders.

Californians vote by mail in large numbers, and ballot counting is a slow process. Leads often shift as the tally drags on for days or even weeks. Early tallies showed Ms. Bass winning 36.6 percent of the vote with about 48 percent of the expected vote in. Ms. Raman had about 21 percent and Mr. Pratt about 30 percent.

Ms. Raman, 44, a City Council member, has been compared to New York’s charismatic progressive mayor, Zohran Mamdani. Mr. Pratt, 42, a former star of the reality show “The Hills,” used his campaign to channel anger on the city’s Westside after a historic wildfire ravaged Pacific Palisades, the wealthy coastal enclave where he had lived.

The race for the second spot on the November ballot remained unclear. Ms. Raman appealed to a base of young urban progressives, while Republicans, who represent only about 15 percent of the city’s voters, coalesced around Mr. Pratt.