Former presidential strategist Steve Bannon is rebuffing President Donald Trump’s plea for him to retreat in his war on the Republican establishment, personally boosting the candidacy of a challenger to incumbent Sen. Jeff Flake.

Bannon plans to appear with Arizona Senate candidate Kelli Ward on Tuesday as she announces another bid for the Senate, this time against freshman Flake. Ward lost last year to Republican Sen. John McCain, who went on to won a sixth term.

The pair will participate in a program headlined by conservative radio host Laura Ingraham in Scottsdale, Arizona, a day after the political action committee affiliated with Bannon said it would support Ward, a former Arizona state senator.

Bannon has said he is “declaring war on the Republican establishment” and that he intends to lead a “populist nationalist conservative revolt,” to clear the way in Congress for Trump’s stalled legislative agenda.

Appearing with GOP Senate Majority Leader Mitch McConnell in Washington on Monday, Trump said he would try to discourage Bannon from going after all Republican senators.

“Some of the people that he may be looking at, I’m going to see if we talk him out of that, because frankly, they’re great people,” Trump said during a joint news conference with McConnell.

Bannon is promoting a field of primary challengers to take on incumbent Republicans in Congress, especially the Senate. He has said he plans to recruit challengers for every GOP senator standing for re-election next year except Ted Cruz of Texas.

Arizona’s Flake, seeking a second term, has been among the Senate Republicans’ most outspoken Trump critics.

“Americans are tired of the inaction from the Washington swamp and demand Senate Republicans get off their backsides and pass President Trump’s America First agenda,” Ed Rollins, chief strategist for Great America PAC, said in a statement Monday announcing its support for Ward.

The Bannon-backed group also announced Monday it was supporting retired Marine Kevin Nicholson in Wisconsin over state Sen. Leah Vukmir in the GOP primary to challenge Sen. Tammy Baldwin, a Democrat seeking her second term.

Nicholson, a former Democrat, is among a list of outsiders Bannon is backing, including Mississippi state Sen. Chris McDaniel, who lost his challenge to Sen. Thad Cochran in 2014.

The group backed Roy Moore in his Alabama runoff with Sen. Luther Strange, the preferred candidate of McConnell. Moore defeated Strange.

A key goal of Bannon’s is to see McConnell dumped as Senate GOP leader, while also getting the president’s agenda, including the dismantling of the 2010 Affordable Care Act and major tax cuts, enacted.

But McConnell argued that some conservative Republicans nominated in the 2010 and 2012 campaigns lost in competitive races, or in states where Republicans would have been expected to win, because they weren’t able to “appeal to a broader electorate in the general election.”

“You have to nominate people who can actually win, because winners make policy and losers go home,” McConnell said.