When Donald Trump arrives in Phoenix, he has a key choice to make that could have implications for his legislative agenda. Does he continue to embrace Kelli Ward, the challenger to incumbent Jeff Flake, who has been attacked by Mitch McConnell’s PAC as “Chemtrail Kelli”? Or does Trump make nice in order to pull the GOP together for a tough budget fight and potentially another shot at ObamaCare repeal?

Politico frames this as a question, but … we all know the answer to this, right?

President Donald Trump faces a decision on Tuesday evening with profound implications for his already strained relationship with the GOP: whether to attack a vulnerable Republican senator on his home turf.

While White House officials won’t say exactly what’s on Trump’s agenda when he holds a campaign-style rally here, there is a widespread expectation that he will go after GOP Sen. Jeff Flake, a loud critic of the president who recently published an anti-Trump manifesto, “Conscience of a Conservative.”

In the days leading up to Trump’s Arizona trip, Senate GOP leaders have implicitly warned Trump that attacking Flake, who faces a treacherous path to reelection, would only serve to further rupture his relationship with a congressional GOP wing that he’s grown increasingly isolated from in recent weeks. It came after Trump, in a tweet after the Phoenix event was announced, called Flake “toxic.” The president had earlier threatened to spend as much as $10 million to take out the incumbent Republican.

Senate Majority Leader Mitch McConnell, Majority Whip John Cornyn, and National Republican Senatorial Committee Chairman Cory Gardner all declared that Flake had their full support.

The obvious answer is that Trump will promote Ward and attack Flake. Flake has been openly critical of Trump for months, and as anyone who has paid attention to politics since mid-2015 knows, Trump always punches back. That’s true even when it may conflict with his strategic interests, such as getting enough votes for his border wall and other budget priorities. Republicans will have to hold together on the budget starting in two weeks, and targeting your party’s own incumbents for primary challenges isn’t the best way of unifying a caucus. Doesn’t matter — Flake criticized Trump, and Trump has to flex his muscles. Period.

GOP leadership made its feelings well known in this 77-second attack ad on Ward. The McConnell-linked Senate Leadership Fund wants to remind voters in Arizona that Ward has a track record of conspiracy thinking, and not just about chemtrails:

That’s really three ads rolled up into one: chemtrails, her odd idea that “restraint” should be our governing strategy for ISIS, and Ward’s highly inappropriate campaign to get John McCain to resign so she could be appointed to his Senate seat. Ward even tried to get Flake to endorse that effort, but he pronounced himself “dumbstruck” by her comments instead. When it comes time to start buying ads in Arizona, expect to see those three themes fleshed out more fully on television. For now, let’s just call this a statement of purpose.

On the other hand, Flake’s not exactly riding a crest of popularity with these constituents at the moment, either. Attacks on Flake will be red meat for the Trump supporters who show up to this rally, with Ward’s colorful track record a side issue. All that does is add incentive for Trump to attack his party’s leadership and push those voters to toss Flake aside, even if it means opening up a relatively safe Senate seat for Democrats — which it would surely do with Ward. Trump himself only got 48% of the vote in November, besting Hillary Clinton by 3.5 points in a state where Libertarian Gary Johnson’s 4.1% showing may have made the difference between victory and defeat.  Toss aside a libertarian-leaning conservative for an InfoWars favorite, and don’t be surprised if Arizona Democrats put up a strong fight for that seat next year. And don’t be surprised if the war between McConnell and Trump creates a rare form of gridlock in single-party governance, too.