Donald Trump's rally Thursday evening in Costa Mesa is expected to draw loyalists as well as protesters.
The rally comes two days after backers and opponents of Trump clashed outside Anaheim City Hall before the City Council voted on a resolution condemning the presidential candidate and GOP front-runner. The resolution was not approved.
Protesters in Anaheim used pepper spray, and several people were treated by paramedics.
Trump is leading in several recent polls in California. He has both supporters and detractors in Orange County. The county remains Republican, but it's not the stronghold it once was.
Republican registration is now at about 40%, down from nearly 60% a generation ago. Though Republicans still outnumber Democrats in Orange County, their shrinking ranks hurt the GOP on the statewide level.
The Democratic Party of Orange County and Orange County Young Democrats announced Wednesday they are coordinating a protest against Trump on Thursday in Costa Mesa.
"We do not believe that there is any room for racism, sexism, religious bigotry, disregard for international law, violence or any other such phenomena in our political discourse," the Orange County Young Democrats said in a statement. "As such, we expressly condemn Donald Trump, declare that his values are not Orange County's values, and we urge all other citizens of Orange County to do the same."
California's presidential primary is June 7, though many voters are expected to cast their ballots by mail before then.
Tickets for Trump's Costa Mesa rally are free for those who register at www.donaldjtrump.com/schedule. No banners, posters, signs, GoPros, selfie sticks or professional cameras with detachable lenses, tripods or monopods will be permitted.
The fairgrounds are at 88 Fair Drive.
Times Community News writer Bradley Zint and Los Angeles Times staff writer Michael Finnegan contributed to this report.