In a potential major upset in the making, San Rafael Councilman Marc Levine held a slight but steady lead over incumbent Assemblyman Michael Allen on Tuesday night in their battle for the 10th Assembly District seat.
With all precincts in, Levine held 50.6 percent of the votes to Allen's 49.4 percent.
"I'm cautiously optimistic about the outcome tonight," Levine said from his campaign party at Aurora Art Studios in San Rafael.
Levine never trailed throughout the evening. The outcome could hinge on about 106,000 mail-in ballots that went out in Sonoma and Marin counties.
David McCuan, a political scientist at Sonoma State University, said a Levine victory would be a "huge" blow for the Democratic Party establishment in Sacramento and for Assembly Speaker John Perez.
The Democratic Party steered a significant amount of money and resources to back Allen, a former union leader who rose quickly through the ranks of power in his first Assembly term to become assistant majority floor leader. Many observers gave Levine no chance of winning.
"If Levine defeats the No. 4 guy in Sacramento — which Allen is — that is huge not only for Democrats in California, but also for the future of Perez as speaker. That's how big this is," McCuan said.
Allen and Levine were vying to represent voters in a newly created district that spans Marin County, part of Santa Rosa and portions of western and southern Sonoma County.
The pair earned the right to compete for the district seat under California's new top-two primary system. The race gained attention in part because it was one of about two dozen in the state pitting members of the same party against one another in the general election.
Allen did not immediately return a message seeking comment Tuesday.