Outgoing Sen. Jeff Flake on Wednesday dismissed Joe Arpaio’s bid for his Arizona Senate seat in 2018, laughing off the controversial former sheriff as a fringe candidate whose campaign will quickly fizzle.

“You’d better write about it and talk about it fast because it won’t last long,” Flake said in an interview with CNN.

Flake, a Republican, has criticized his own party for the better part of two years for nominating controversial insurgent candidates for high office such as President Donald Trump in 2016 and former Alabama judge Roy Moore in last year’s Senate special election there. Flake went so far as to donate $100 to the campaign of Moore’s opponent in the race, Democratic Sen. Doug Jones.

Flake seems to have likened Arpaio, 85, who is embroiled in a lawsuit with Flake’s son Austin, to those of the GOP candidates he has previously denounced.

He will not support Arpaio if he becomes the GOP nominee, he said in the interview.

“No, no, no, no. Not at all,” Flake said. “That’s not our best foot forward as Republicans.”

“There’s hardly been an election cycle from the early-’90s that Sheriff Joe hasn’t talked about running statewide,” Flake continued. “He floats it out there for a while and then pulls back. So I don’t expect that it will go very far.”

Arpaio responded to Flake’s criticism, calling him out on his decision not to run again.

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“He’s saying that I’m not going to last more than a month, that I’ll leave, but what about him leaving?” Arpaio said. “He didn’t have the guts to face the people to get re-elected. At least I got the guts to face all the detractors — Democratic Party, you name it.”

Arpaio jumped into the state’s GOP primary on Tuesday, touting his “unwavering” support of President Donald Trump, who pardoned Arpaio last year after the former Maricopa County sheriff was convicted of defying a court order in a racial profiling case.

“I am running for the U.S. Senate from the Great State of Arizona, for one unwavering reason: to support the agenda and policies of President Donald Trump in his mission to Make America Great Again,” Arpaio tweeted Tuesday morning.

Arpaio’s entrance in the race could complicate things for former state Sen. Kelli Ward, who had attempted to cast herself as the most pro-Trump candidate in the race.

GOP Rep. Martha McSally is expected to join the race for the GOP nod as well. McSally is more closely aligned with Senate Majority Leader Mitch McConnell, who listed her as a top recruit. 

The beef between Flake and Arpaio is not just political, but personal.

Flake’s son Austin filed a malicious-prosecution lawsuit against Arpaio, saying the sheriff abused his power in 2014 and improperly brought felony animal cruelty charges against him and his then-wife in order to gain publicity and hurt the senator’s image. The case was later dismissed.

But the resulting media coverage and death threats from Arpaio backers broke up the younger Flake’s marriage, the lawsuit alleges.

The prosecutor in the original criminal case said Arpaio’s office did not pressure her to prosecute the couple, and in a court deposition, Arpaio did not accept responsibility for bringing the charges against the couple.

Arpaio had floated challenging Flake, and said he was considering running after Flake retired. But Arpaio said multiple times in the past that he was considering running for office — and ended up not running. 

Arpaio has become a prominent figure among conservatives with hard-line stances on illegal immigration, who favor his controversial tactics.  While sheriff he set up a “Tent City” jail, which was criticized for creating cruel conditions for inmates. He also led a crackdown on illegal immigration.

Trump won the state by 4 points in 2016. Inside Elections with Nathan L. Gonzales rates the race a Tossup.