Donald Trump has shrugged off a stinging personal attack on his presidency from senior fellow Republican Mitt Romney.
Mr Romney, who stood and lost for the Republicans against Barack Obama in 2012, suggested in an article that Mr Trump was not fit to be president.
Mr Trump had not “risen to the mantle”, he wrote in the Washington Post.
The winner of the 2016 presidential election hit back by tweeting, “I won big and he didn’t.”
Mr Trump drew a comparison with Jeff Flake, an outgoing Republican senator who also attacked him last year.
But the president sounded conciliatory, calling for Mr Romney to be a “team player”.
The timing of the article, just two days before Mr Romney is sworn in as senator for Utah, has prompted some to speculate he is positioning himself as a challenger to Mr Trump for the Republican presidential nomination.
What did the opinion piece say?
In the article, Mr Romney praised many of Mr Trump’s policies, such as his tax reforms and appointment of conservative judges, and his crackdown on “China’s unfair trade practices” – polices which he said “mainstream Republicans” had promoted for years.
But he went on to say: “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.”
Mr Romney said he would support the president in policies he thought were in the best interests of Utah or the US but speak out against actions “that are divisive, racist, sexist, anti-immigrant, dishonest or destructive to democratic institutions”.
“The appointment of senior persons of lesser experience, the abandonment of allies who fight beside us, and the president’s thoughtless claim that America has long been a ‘sucker’ in world affairs all defined his presidency down,” he wrote.
“Trump’s words and actions have caused dismay around the world.”
The world “needs American leadership”, he argued, and “the alternative… offered by China and Russia is autocratic, corrupt and brutal”.
How have other Republicans reacted?
Ronna McDaniel, chairwoman of the Republic National Committee and a niece of Mr Romney, described her uncle’s article as “disappointing and unproductive”.
Mr Trump’s manager for the 2020 presidential campaign went so far as to accuse Mr Romney of jealousy.
Meanwhile, the New York Times, the liberal daily regularly attacked by Mr Trump, commented that much of the essay “sounded like the makings of a primary challenge against Mr. Trump from Mr. Romney”.
What kind of relationship do the two men have?
A complicated one. During the 2016 campaign, Mr Romney said Mr Trump had neither “the temperament nor the judgement to be president” while Mr Trump called Mr Romney a “choke artist” and called his bid for the presidency in 2012 “the worst ever”.
The same year though, the pair met for dinner amid reports Mr Trump was mulling appointing Mr Romney as his secretary of state.
Mr Romney has also taken issue with Mr Trump labelling the press the “enemy of the people” as well as his response to a violent far-right rally in Charlottesville.
When the US Congress reconvenes on Thursday, Mr Trump faces a new challenge on the domestic front – in November’s mid-terms the Republicans strengthened their hold of the Senate but lost the House of Representatives.