(CNN) Former Wyoming Sen. Alan Simpson isn't a big Donald Trump fan.
In an interview with NBC News, Simpson called Trump, among other things, a "spoiled brat" and said that "this guy is so full of himself that he would overturn every kind of rule of law or Constitutional process because of his own ego, which is twisted."
Simpson, a Republican, acknowledged that he voted for Trump in 2016 but noted that "I'll never vote for him again -- that's for goddamn sure."
Simpson is speaking out against Trump even as he appears in a new ad for Wyoming Rep. Liz Cheney, who faces long odds of winning a primary fight later this summer against Trump-endorsed challenger Harriet Hageman.
In the ad, Simpson, who spent 18 years representing Wyoming in the Senate, is identified simply as "Al."
"Join me in voting for Liz Cheney on August 16th," the former senator, who is 90, says at the conclusion of the Cheney ad.
It's unclear how much influence Simpson retains in the state. He hasn't served in the Senate since 1997 although his father, Milward, served as both the state's senator and governor -- so the Simpson name is known in the state.
His reputation in the Senate was as a moderate -- and given that the party has moved considerably to the ideological right since he left, it's hard to even place Simpson in the current iteration of the Republican Party.
Using Simpson -- and his decidedly anti-Trump views -- appears to be part of a larger effort by Cheney to court Democrats (and unaffiliated voters) in advance of the August 16 primary. Of late, Cheney's campaign has sent mailers to Democrats in the state informing them of how to change their party affiliation in order to vote for her. The New York Times also reported recently that there is a link to information on how to switch party affiliation on Cheney's website.
That series of tactics suggest that Cheney and her advisers have concluded that they have little chance to win a primary race in which only Republicans vote. Trump has made defeating her one of his top priorities in 2022; she is one of 10 House Republicans who voted to impeach Trump for his role on January 6.
Four of the 10 are retiring this fall. Another -- South Carolina Rep. Tom Rice -- lost in a primary earlier this month. California Rep. David Valadao advanced to the general election. Four -- Cheney as well as Washington Reps. Dan Newhouse and Jaime Herrera Beutler as well as Michigan Rep. Peter Meijer -- face August primaries against Trump-backed foes.
While all four are considered in danger, Cheney is clearly the most vulnerable of the group -- as she is the most high-profile critic of Trump in Republican politics. His anger at her has only grown during her time as vice chair of the January 6 select committee in the House, which he has described as a "witch hunt."