WASHINGTON — Mitt Romney, the 2012 GOP presidential nominee and incoming Utah senator, has quickly set himself apart from other Republicans in the new Congress with a blistering attack on President Donald Trump’s leadership and character, triggering what could become a new rivalry in the GOP ranks.

Romney put to rest expectations that he would take his time getting his footing in Washington. Instead, he penned an op-ed in The Washington Post, two days before being sworn into office, that said Trump’s “conduct over the past two years, particularly his actions last month, is evidence that the president has not risen to the mantle of the office.”

Trump replied by tweeting he hoped Romney wouldn’t follow in the footsteps of Sen. Jeff Flake, R-Ariz., who often criticized Trump and paid the price, opting to retire rather than risk defeat in a GOP primary.

“Here we go with Mitt Romney, but so fast! Question will be, is he a Flake? I hope not,” Trump tweeted. “Would much prefer that Mitt focus on Border Security and so many other things where he can be helpful. I won big, and he didn’t. He should be happy for all Republicans. Be a TEAM player & WIN!”

By taking on Trump so early in his Senate career, Romney could be picking up where Flake and Sen. Bob Coker, R-Tenn., another retiring senator, left off.

Both Republicans were vocal GOP critics of Trump, and their retirements left some wondering whether any other Republicans would be willing to publicly criticize the president. Democratic Sen. Dick Durbin, D-Ill., noted that almost half of the Senate Republicans are up for re-election in 2020.