When President Donald Trump takes the stage this week at a rally in Arizona, the state's junior senator will be nowhere to be seen. But Trump is likely to save some choice words for Sen. Jeff Flake.
The senator is currently in an escalating feud with the president - a spat that illustrates the upside-down world of Republican politics heading into the 2018 elections. Flake is a Republican incumbent who is beloved by many high-ranking party officials, and he is trying to hold onto a seat that the party needs to keep control of Congress. Meanwhile, the president from his own party is actively campaigning against him and Flake is returning the punches.
The dynamic highlights the ongoing turmoil in the GOP over how to closely to align with a deeply unpopular president who still retains a devoted base of supporters - voters candidates like Flake will need to win.
Flake, who published a book last month questioning Trump's conservative values, says he mainly backs the president. But he's shown he's willing to slam his party's leader despite knowing the president will hit back - and hard.
That happened this past week, when the president called Flake "weak" in a tweet and touted his primary opponent, former state Sen. Kelli Ward.
The president's criticism came just two days after Flake himself took a backhanded swipe at Trump over his widely panned response to the white supremacist violence in Virginia, saying "we can't claim to be the party of Lincoln if we equivocate in condemning white supremacy."
Flake's colleague, Arizona Sen. John McCain, defended him, saying in a tweet that Flake is "a principled legislator & always does what's right for the people of #AZ. Our state needs his leadership now more than ever."
Trump then announced he was heading to the senators' home turf on Tuesday to rally his fans in Phoenix.
Other Republican senators have started to follow in Flake's footsteps and move away from Trump. South Carolina Sens. Tim Scott and Lindsey Graham both criticized his comments on the Virginia violence, and Tennessee Sen. Bob Corker questioned Trump's stability and competence after the president said white supremacists don't bear all the blame for the melee in Charlottesville.
Flake's moves come with some risk in a state with a devoted base of Trump supporters. Still, a look at McCain's 2016 re-election bid can give him some solace.
McCain won his own primary election against Ward last year by more than 11 percentage points and went on to beat the Democrat in the general election by 13 points, even after he broke with Trump in the month before the election and refused to vote for him. Trump, meanwhile, won Arizona by fewer than four percentage points, a reminder of the state's moderate tilt.
Still, Trump got nearly 150,000 more votes than Flake did when he ran in 2012, a reminder of Trump's power to draw in new voters. Republicans debating a break from the president must also be ready to weather a break from some of his voters.
Flake has been trying to walk a careful line. He's voted with Trump on important issues but has been more willing than most GOP lawmakers to criticize him and did not endorse him last year.
"I think what Arizona expects of a senator is someone who will work with a president when he's right and oppose him when they think he's wrong," Flake told The Associated Press in an Aug. 10 interview. "That's what I'm doing and that's what I've done whether we've had a Republican president or a Democratic president."
Flake brushed aside criticism from Trump and declined to discuss Ward's campaign and emerging national profile, saying "I'll leave her to her campaign. I'll work mine."
Ward, a physician who drew only 39 percent of the vote in a primary fight against McCain last year, is seen as a longshot by top Arizona Republicans. She hurt herself last month by urging McCain to step down following his brain cancer diagnosis and suggesting she should be considered to replace him.
Flake said at the time he was "dumbstruck" by her comments.
But Arizona Republicans are torn, just like the rest of the country's GOP voters amid an intra-party feud.
Sheri Schmeckpeper, a Republican from the Phoenix suburb of Gilbert, voted for Trump and still backs him despite his recent troubles. She believes he's getting a raw deal from the media and Republican critics - and she doesn't think too highly of Flake.
"I think he's too much of a career politician and we need to replace him," said Schmeckpeper. "I don't think he represents the conservative viewpoint, the constitutional viewpoint."
That opinion is a danger for Flake, who calls his book "Conscience of a Conservative" - the same as the famous tome written by the late Arizona Sen. Barry Goldwater, a bedrock of conservative philosophy in American politics.