Washington (CNN) Senate Majority Leader Mitch McConnell said he "can't imagine" President Donald Trump not backing Mitt Romney's campaign for a US Senate seat from Utah.

"I can't imagine that he's not," McConnell told The New York Times when asked on Friday afternoon if Trump was comfortable with Romney. "We don't want to lose the seat, and this looks like a pretty formidable candidate."

Romney officially announced his candidacy Friday for retiring GOP Sen. Orrin Hatch's seat. In the video announcing his candidacy, Romney noted that Utah "welcomes legal immigrants from around the world" and "Washington sends immigrants a message of exclusion." On Friday, he said he was open to new gun measures , such as enhanced background checks.

McConnell expressed his own confidence in the ability of the 2012 Republican presidential nominee to be immediately useful in the Senate.

"He will come in here with a level of national identity and respect that will make him effective from day one," the majority leader said.

McConnell conceded in his Times interview that it's likely Republicans will lose seats in the House and Senate in the midterm elections.

"History tells you that, the fired-up nature of the political left tells you that," he said. "We go into this clear-eyed that this is going to be quite a challenging election."

Trump and Romney have previously been involved in a feud that reached its apex in March 2016, after Romney denounced Trump, who was then the front-runner for the Republican presidential nomination, in a speech at the University of Utah.

Romney called Trump a "con man," and claimed his "domestic policies would lead to recession" while questioning his temperament and judgment.

Over the next few days, Trump repeatedly fired back on Twitter. He called Romney a "disaster candidate" and a "mixed up man who doesn't have a clue."