SACRAMENTO, Calif. (AP) — California Assemblymen Brian Dahle and Kevin Kiley are like-minded colleagues, but the two conservative Republican lawmakers are engaged in a nasty fight Tuesday.

The candidates want to fill one of two vacant state Senate seats, a battle that may reflect their party’s larger struggle for relevance in elections overshadowed by President Donald Trump.

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Either Dahle or Kiley will succeed fellow Republican Ted Gaines, who won a seat on the state Board of Equalization in November.

Republicans are also likely to eventually retain the winner’s Assembly seat. Kiley represents northeastern Sacramento suburbs, while Dahle’s district, much like the 1st Senate District, sprawls across nine northeastern California counties from the capital city to the Oregon and Nevada borders.

Four hundred miles (644 kilometers) to the south, Long Beach City Councilwoman Lena Gonzalez is heavily favored to win the 33rd Senate District seat in southeast Los Angeles County that was held by fellow Democrat Ricardo Lara until he was elected insurance commissioner. She faces Republican Cudahy Councilman Jack Guerrero in a district where 55% of voters are registered Democrats, to Republicans’ 12%.

That means the outcome in either race isn’t expected to change Democrats’ overwhelming legislative majorities.

Yet the fight between the two Republican colleagues has featured allegations of doctored photographs, fake endorsements — and a mysterious “vote-shaming” mailer threatening to publicize the names of those who fail to vote in Tuesday’s special general election.

The sparring is also another test run for Trump’s influence on voters, said Phillip Escamilla, chairman of the public policy department at William Jessup University, which is located in the district.

“I think California Republicans are trying to figure out, going into 2020, whether being affiliated with the current administration helps their cause or not,” Escamilla said. He cited an independent mailer linking Dahle with Trump “in a negative light” in a likely attempt to tar Dahle in the minds of Democratic voters who may decide the election’s outcome.

Moreover, with no statewide officeholders, no apparent farm team and just 10 Republicans in the 40-member Senate, each GOP senator may play on outsize role in the party’s future, he said.

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“You could look at it as a fight for leadership of the party, from one standpoint,” said Escamilla.

Each candidate has spent about $1 million and another nearly $1 million in outside spending has benefited Dahle.

Dahle, 53, of Bieber, is a former Assembly Republican leader backed by establishment groups like real estate agents, peace officers and prison guards.

“He obviously has a bit more institutional support,” said Rob Pyers, research director at the nonpartisan California Target Book that tracks legislative races.

While both men have solidly conservative voting records, Dahle’s official biography says he “works across party lines for job creation and economic development.”

Kiley, of Rocklin, is nearly two decades younger at age 34 and has four years less experience in the Assembly. His main financial backing had come from wealthy supporters of charter schools who have not spent independently to boost this campaign, said Pyers.

He was assigned to the “dog house” — the Legislature’s tiniest cubbyhole office — after offending the Assembly Education Committee’s chairwoman and Assembly Speaker Anthony Rendon with a heated round of questioning this spring.

Each candidate has challenged the accuracy of advertising supporting his opponent. But the one raising the most eyebrows was a mailer sent by a group calling itself the Northern California State Voter Project, listing some residents’ voting history and threatening to reveal others who fail to vote.

“The idea that someone would feel threatened to vote sort of goes against the idea that we have the freedom to vote,” said Escamilla.

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Secretary of State Alex Padilla’s office is reviewing whether the mailer violates state law.