Sen. Rand Paul denounced newcomer colleague Mitt Romney for writing a critical op-ed about President Trump, and accused the Utah Republican of damaging the GOP by "virtue signaling."

“It’s a big mistake and it really gets things off on the wrong foot for the senator from Utah,” Paul told reporters Wednesday.

Paul characterized the column by Romney, who will represent Utah in the U.S. Senate beginning Thursday, as “name calling” and said Romney’s view is not shared by most in the GOP.

“I think it’s a minority opinion,” Paul told reporters Wednesday. “Most people don’t criticize a president’s character.”

Romney, the former Massachusetts governor and GOP presidential nominee, authored a scathing op-ed in the Washington Post Tuesday accusing Trump of a “glaring” shortfall in character and presidential leadership that has hurt America’s standing abroad and has caused a deep national divide.

Romney accused Trump of resentment and name calling and said Trump, despite installing positive economic and trade policies, “has not risen to the mantle of the office.”

[Related: Trump responds to Mitt Romney: 'I won big, and he didn't']

Paul, R-Ky., a libertarian who often bucks his own party leadership, defended Trump and called Romney’s attack misplaced and unhelpful for the Republican Party.

“I think this is going to be an anomaly,” Paul said of the Romney op-ed. “And I think the senator from Utah may have misjudged.”

Paul called Trump’s 2016 victory by way of Wisconsin, Michigan, Pennsylvania, and Ohio, “extraordinary,” and noted Romney was unable to win over the rust belt region.

Paul said Romney should not run for president again, and said he wouldn't do well if he tried.

“I don’t think there’s an appetite for a Romney run within the Republican Party, nor do I think the Romney establishment, big government Republican is popular enough to win the general election," he said.