Dennis Rodoni will face a challenger as he seeks a third term as District 4 supervisor: Francis Drouillard, a Novato engineer and a member of the Marin County Republican Central Committee.

Mr. Drouillard filed his papers on Friday, the deadline for candidates to declare their campaigns. Echoing the MAGA slogan of Donald Trump, his campaign announcement proclaims: “We can make living in Marin County magnificent again.”

He promises to crack down on crime, support the police and be vigilant about potential voter fraud. His website also derides “RINOs”—Republicans in Name Only—and “woke enviros.”

“We must end the public drug use and alcoholism that are drivers of homelessness and mental health problems,” his announcement states. “Our current ‘carrot only and no stick’ approach allows grifters to siphon limited resources to house the unfortunate while preventing drug addicts, alcoholics, and those with mental health issues from getting the treatment they need.”

Mr. Drouillard advocates a return to paper ballots and suggests on his website that Democratic candidates have received an implausible share of the vote in California. “Although the vast majority of those conducting our elections are honest and hardworking, it only takes one or two bad apples to corrupt our election results with mass mail-in ballots and an electronic voting system,” he wrote in an entry on his campaign blog. “It is my goal to implement changes that will restore confidence in our elections.”

Mr. Drouillard, a 67-year-old Michigan native, founded and chairs an organization called the Marin County Election Integrity Committee, which sends volunteers to observe local election sites for signs of fraud. According to his campaign biography, he is a bridge designer for OPAC Consulting Engineers of San Francisco.

As chairman of the Novato Police Advisory and Review Board, he has been a strong advocate for the men and women in blue. “We must allow law enforcement to stop the cancer of personal and retail theft spreading into Marin County from San Francisco and the East Bay,” his campaign announcement states.

His website features an article that said gang members were using “jammers” to disable burglar alarms in wealthy Detroit suburbs. In a blog post, Mr. Drouillard suggests that gang members could soon infiltrate West Marin. “There are plenty of ‘transnationals’ here illegally to develop organized teams of burglars provided with alarm-jamming equipment from nearby ‘sanctuary’ cities such as Oakland and San Francisco,” Mr. Drouillard warns on his website. “Both cities have adopted ‘defund the police’ policies that allow criminal activity to thrive within their jurisdiction.”

Mr. Rodoni, an Olema resident and contractor by trade, said he didn’t know much about Mr. Drouillard’s background, but welcomed the competition. “A competitive election gives me a chance to talk about important issues, what we achieved over the past seven years, and what we hope to achieve over the next five years,” he said.