Rep. Adam Schiff’s (D-Calif.) campaign for Senate is seeking to kneecap his Democratic opponents in next month’s primary by boosting the Republican in the race, Steve Garvey.

“Steve Garvey, the leading Republican, is too conservative for California — he voted for Trump twice, and supported Republicans for years, including far-right conservatives,” the narrator says in an ad released by Schiff’s campaign on Thursday.

Schiff holds a lead in the race, according to several polls conducted recently, while Garvey and Rep. Katie Porter (D-Calif.) are battling for second place, and Rep. Barbara Lee (D-Calif.) trails behind them.

California has a “top-two” primary system to determine which two candidates advance to the November general election. It’s such a deep-blue state, there’s a good chance both candidates will be Democrats. But if Garvey, a former baseball star and first-time candidate, gets enough votes to make it to the runoff, Schiff can avoid a messy and expensive battle with a fellow Democrat and coast to a victory.

Democrats have strategically lifted up a conservative opponent to help their campaigns before ― recently, in the 2018 California gubernatorial race and in the 2012 Missouri Senate race, when then-Sen. Claire McCaskill (D-Mo.) ran ads boosting an extreme candidate in the GOP primary, who she went on to defeat in the general election.

Porter criticized Schiff’s ad, saying he “knows he will lose” to her.

“That’s what this brazenly cynical ad is about—furthering his own political career, boxing out qualified Democratic women candidates, and boosting a Republican candidate to do it,” Porter added. “We need honest leadership, not political games.”

Porter and Schiff took several jabs at each other in a debate last month, over issues like accepting money from oil companies and their accomplishments in Congress.

Garvey, meanwhile, defended former President Donald Trump and said he didn’t believe President Joe Biden has been “good for this county,” which could cost him votes in California, where Trump is wildly unpopular.

Garvey lags far behind Schiff and Porter in fundraising and his campaign has few resources to pay for spots of his own in a state where advertising is notoriously expensive.

Garvey’s campaign responded to Schiff’s ad on Thursday by denouncing “trite political hatchet jobs” and “divisive rhetoric that aims to separate ourselves.”