Former U.S. presidential candidate Mitt Romney speaks at the Utah County Republican Party Lincoln Day Dinner, in Provo, Utah, U.S. February 16, 2018.
Romney responded on Twitter by thanking Trump for the endorsement, adding he hoped over the campaign to earn the support of Utah's citizens. Trump wrote Monday evening that Romney "will make a great Senator and worthy successor" to the retiring Orrin Hatch.
The two have not always gotten along in the past.
"Utah voters rejected numerous things that Trump was very outspoken about, and they rejected sort of the tone and tenor of his candidacy", said Katie Packer Beeson, a GOP consultant who served as Romney deputy campaign manager in 2012 and led an anti-Trump super PAC in 2016.
A Salt Lake Tribune poll last month showed Romney with the support of 85 percent of Utah Republicans - and 18 percent of Democrats.
Romney on Friday announced his long-expected Senate bid in his adopted state of Utah with a low-key rollout meant to duck roiling Republican divisions and avoid signaling that he will play the role of foil to Trump.
In the 2012 presidential race, Romney won the Utah presidential contest with 73% of the vote against President Obama.More news: Germany expects freed journalist to be allowed to leave Turkey
Mitt Romney has used words like "phony", "fraud" and "con man" to describe Donald Trump.
That Romney has softened his tone on Trump is not entirely surprising.
Trump also reportedly tried to convince Sen. Trump publicly considered Romney for Secretary of State - but instead gave the position to former Exxon Mobil CEO Rex Tillerson. Among the president's comments: "Especially in light of the advent of Antifa, if you look at what's going on there, you know, you have some pretty bad dudes on the other side also". In the run-up to the December special election, Romney stated that Moore's election "would be a stain on the GOP and on the nation".
"MittRomney has announced he is running for the Senate from the wonderful State of Utah".
Romney's designs on the Utah seat were known well before he announced last week.
Some see recent public niceties between the men as evidence that they're burying the hatchet; however, Trump's endorsement will likely only solidify his popularity among his most enthusiastic base: Mormons.