Mitt Romney performed a textbook U-turn Monday, accepting the endorsement of Donald Trump for the Utah Senate seat.

Trump, who once called Romney “the dumbest and worst candidate in history,” posted a surprise endorsement on Twitter Monday after Romney officially announced Friday he would run for the seat vacated by Sen. Orrin Hatch later this year.

Prior to Trump’s tweet, it remained unclear if the president would bestow his blessing on the man he said “choked like a dog” during the 2012 presidential campaign.

Romney responded a few moments later:

Even though Romney once said:

As well as this:

The sporadic Trump-Romney bromance:

Trump endorsed Romney in 2012 after the candidate visited him at Trump Tower. Romney lavished praise on the businessman, saying he has “an extraordinary ability to understand how our economy works and to create jobs.”

Fast forward to 2016 and the relationship had soured. In March of that year Romney gave a 20-minutes speech urging GOP votes not to let Trump reach the required 1,237 delegates during the primaries.

The same day Trump reminded his supporters that Romney "begged" for his endorsement in 2012: “I could've said, ‘Mitt, drop to your knees.’”

Trump told a cheering crowd in April 2016 that Romney “choked like a dog” against Obama.

By November Romney and Trump were back together, enjoying a candlelit dinner in Manhattan to discuss the possibility of Romney becoming Secretary of State. The position ultimately went to Rex Tillerson, with Trump aide Roger Stone saying the president was only “toying” with his former foe.

Romney returned to criticizing Trump in August 2017, slamming his controversial comments over the violence in Charlottesville, which “caused racists to rejoice, minorities to weep, and the vast heart of America to mourn.”

As recently as December, Romney attacked Trump for supporting the alleged sexual predator Roy Moore, calling it “a stain on the GOP and on the nation.”

A day later, White House adviser Kellyanne Conway told CNN that Trump and Romney have a “great relationship.”