Outgoing Ohio Gov. John Kasich gave Senator-elect Mitt Romney (R-UT) a virtual pat on the back Tuesday, endorsing Romney’s Washington Post op-ed bashing President Donald Trump’s character.

“Welcome to the fray,” wrote Kasich, linking to the op-ed published Tuesday.

The outgoing Ohio governor has built a reputation as one of Trump’s most vocal critics, accusing the president of causing political divisions in the U.S. and criticizing Trump over his efforts to combat illegal immigration.

Kasich has mentioned in the past that he is “very seriously” considering a run for president in 2020, although he has not specified whether he would run as an independent or attempt to challenge Trump for the Republican nomination.

Romney, who has also openly criticized Trump since the 2016 presidential election, wrote in the New Year’s Day op-ed that Trump “has not risen to the mantle of the office.”

The two-time former presidential candidate acknowledged that Trump’s policies were in line with mainstream Republicans, but criticized Trump’s character and accused him of dividing the American people.

“With the nation so divided, resentful and angry, presidential leadership in qualities of character is indispensable. And it is in this province where the incumbent’s shortfall has been most glaring,” the incoming Utah senator wrote.

Although many Trump critics from within the Republican Party endorsed Romney’s sentiments, some Republicans defended Trump.

Sen. Rand Paul (R-KY) criticized Romney for being a virtue-signaling “Big Government Republican who never liked Reagan,” while defending Trump for enacting an “actual conservative reform agenda.”

Even Republican National Committee chair Ronna McDaniel, who is Romney’s niece, called Romney’s op-ed “disappointing and unproductive.”

Trump responded to the op-ed Tuesday, saying he wished Romney would “be more of a team player” after he endorsed Romney in his Utah Senate race in the 2018 midterm elections.

“I wish Mitt could be more of a team player,” Trump said. “I endorsed him, and he thanked me profusely.”