Conservative activist Tim Donnelly wants to rid Congress of President Donald Trump’s opponents.

Donnelly’s target, though, isn’t a Democrat. The former Inland assemblyman and GOP candidate for governor recently announced his bid to unseat Rep. Paul Cook, R-Yucca Valley, in California’s 8th Congressional District, which includes part of San Bernardino County.

“I’m running because our district … overwhelmingly supported the president,” Donnelly said in an online video announcing his candidacy. “We sent him to D.C. because he said he would make America great again. And we watched as the Congress – this do-nothing Congress – has stymied him at every turn.”

Candidates like Donnelly, or at least the anger motivating them, pose another potential headache for congressional Republicans already targeted by Democrats in the 2018 mid-term elections. Democrats hope Trump’s unpopularity – especially in deep blue California – sinks GOP incumbents a year from now, particularly in four Orange County districts represented by Republicans, districts that Hillary Clinton won in 2016.

At the same time, Trump remains popular among the GOP base. And Steve Bannon, Trump’s former chief White House strategist, is leading a campaign to unseat Senate Republicans seen as obstacles to Trump’s agenda.

“It is more like a tug of war with a few extra ropes tied to them that are pushing them sideways along with back and forth,” said Marcia Godwin, a professor of public administration at the University of La Verne.

Getting Republicans to the polls will be key to the upcoming contests.

With no compelling GOP candidates for U.S. Senate and governor, Republican voter turnout in California could fall off in 2018, said Jack Pitney, a professor of politics at Claremont McKenna College.

“And in low-turnout primaries, highly ideological candidates such as Donnelly can sometimes win upset victories,” Pitney said. “The same is true for other Republican House members as well. They should not assume that they can merely coast through the primary.”

Bannon, who served as Trump’s campaign manager and runs the Breitbart conservative news website, received a standing ovation at the California Republican Party convention in Anaheim earlier this month.

Moderates melt away?

While the GOP controls Congress, the White House and a majority of state governments, the party has been pushed to the margins in California. As Republican voter registration in California continues to fall, Democrats hold all statewide offices and a supermajority in the state Legislature.

“The underlying dynamic is that the California GOP is shrinking like an ice cream cone on a midsummer day,” Pitney said. “As moderate voters melt away, what is left is a hard right-wing core.”

Bannon used his convention speech to slam Republicans for not supporting Trump and an economic populist agenda. He had particularly harsh words for Sen. John McCain, R-Arizona, and Republican and former president George W. Bush, both of whom have criticized Trump.

“President Bush, to me, embarrassed himself,” Bannon said as the audience booed mentions of McCain and Bush.

Every California House Republican voted to repeal Obamacare, a.k.a. the Affordable Care Act, and by doing so, they gave Democrats a 2018 talking point. But the repeal effort faltered in the Senate, angering Republicans who want Obamacare gone.

In California, divisions among Republicans surfaced in the backlash against then-Assembly Republican Leader Chad Mayes of Yucca Valley, who was roundly condemned within his own party for joining Democrats in a vote to extend California’s pollution-fighting Cap-and-Trade Program.

The furor eventually cost Mayes his leadership post. Mayes, who has said his party needs to change if it wants to be relevant in California, blasted Bannon’s invitation to the state GOP convention, saying it was “a giant step backward and demonstrates that the Party remains tone deaf.”

Two Republicans are running to unseat Mayes in 2018. Mayes reportedly is mulling a run for governor.

‘Keystone cops’

Cook represents a district in which the GOP holds a roughly 5 percentage point edge in voter registration. While Clinton dominated in California overall, Trump won the 8th district with 55 percent of the vote.

“I will back the president’s agenda because I know you back it,” Donnelly, who made a name for himself in the Assembly opposing illegal immigration and gun control, said in his video. “And I’ll have his back because he’s got yours.”

If elected, Donnelly’s agenda includes repealing Obamacare, enhancing border security, ending mandatory vaccinations and defending gun rights.

In a phone interview, Donnelly said he “absolutely” sees his candidacy fitting in with conservatives’ frustration with Republicans in Congress.

“It’s not enough to be in Congress and take up space,” he said. “I think a lot of conservatives are shocked and horrified that the simple campaign promises (like repealing Obamacare) – all of a sudden they can’t do it. They’re Keystone Cops with a purpose” of not wanting Trump to succeed.

In an emailed statement, Cook, a retired Marine Corps colonel and former state lawmaker elected to Congress in 2012, said: “A simple fact check demonstrates the obvious: I’m a Republican, I supported Trump during his election – as I have all Republican presidential nominees in my lifetime – and I’ve worked closely with my colleagues in Congress and our President to replace Obamacare, achieve tax reform, and keep Americans safe.”

“My first priority is always the people of California’s 8th Congressional District, and I’ll always display the independence they expect of me and that they deserve,” Cook added. “That’s why despite opposition from some members of the administration, I voted to impose greater sanctions against Russia and other rogue nations last summer.”

After a failed gubernatorial bid in 2014, Donnelly ran against Cook last year. He narrowly finished out of the top two in the June 2016 primary behind Cook and Democrat Rita Ramirez; California’s primary system sends the top two vote-getters, regardless of party, to the general election.

“For 2018, (Donnelly) might have a better chance of advancing if Democrats focus more on other districts,” Godwin said. “However, Cook is going to be well prepared and well-funded for a rematch.”

A check of federal campaign filings showed no GOP challengers for Reps. Ed Royce, R-Fullerton; Mimi Walters, R-Irvine; and Darrell Issa, R-Irvine, although each face multiple Democratic opponents.

Two Republicans have announced challenges to Rep. Dana Rohrabacher, R-Costa Mesa, and at least two Republicans have filed to run against Rep. Duncan Hunter, R-Alpine, who represents most of Temecula and has been dogged by an ongoing criminal investigation into his campaign finances.

Donnelly said he’s not aware of challengers like him taking on Southern California Republicans in other districts. And Godwin said the 8th district race is “likely to be unique” among the 14 California House districts held by Republicans.

“Only five of the fourteen Republican incumbents in Congress won re-election in 2016 with over 60 percent of the vote,” she said. “There are a large number of Democratic challengers already announced for all fourteen seats.”