BRIDGEWATER, N.J. >> Mitt Romney, the Republican presidential nominee in 2012, has excoriated President Donald Trump for his equivocating response to the violence in Charlottesville, Virginia, and urged him to apologize or risk subjecting the country to “an unraveling of our national fabric.”

Romney’s remarks, posted on Facebook on Friday, mark some of the strongest language from a Republican against Trump after a white supremacist rally in Charlottesville and an attack by a driver that left a woman dead. Trump, on Tuesday, said “both sides” were to blame for Saturday’s deadly violence.

“Whether he intended to or not, what he communicated caused racists to rejoice, minorities to weep, and the vast heart of America to mourn,” Romney wrote. “His apologists strain to explain that he didn’t mean what we heard. But what we heard is now the reality, and unless it is addressed by the president as such, with unprecedented candor and strength, there may commence an unraveling of our national fabric.”

Trump is scheduled to have a rally in Phoenix next week, raising concern about more possible violence. The mayor of Phoenix, Greg Stanton, said in a Twitter post Wednesday that he was “disappointed” that the president would hold a political event “as our nation is still healing from the tragic events in Charlottesville.” Stanton, a Democrat, urged Trump to delay the visit.

In his message to the president, Romney also noted that U.S. military leaders had distanced themselves from the president.

“Our allies around the world are stunned and our enemies celebrate; America’s ability to help secure a peaceful and prosperous world is diminished. And who would want to come to the aid of a country they perceive as racist if ever the need were to arise, as it did after 9/11?” Romney said. “In homes across the nation, children are asking their parents what this means. Jews, blacks, Hispanics, Muslims are as much a part of America as whites and Protestants. But today they wonder. Where might this lead? To bitterness and tears, or perhaps to anger and violence?”

Romney called for the president to apologize.

“He should address the American people, acknowledge that he was wrong, apologize,” Romney wrote. “State forcefully and unequivocally that racists are 100% to blame for the murder and violence in Charlottesville.”

Romney was a leading contender to be Trump’s secretary of state, before the president chose Rex Tillerson. He has generally been muted in the controversies of the Trump administration. But he was among the loudest of Trump’s critics during the campaign: At one point, he derided Trump as a “phony, a fraud” and warned of damage to the Republican party if he became the nominee.

Romney also said during the campaign that he had concerns about Trump’s comments appealing to racists.

“I don’t want to see trickle-down racism,” Romney said on CNN in June 2016. “I don’t want to see a president of the United States saying things which change the character of the generations of Americans that are following. Presidents have an impact on the nature of our nation. And trickle-down racism, trickle-down bigotry, trickle-down misogyny — all of these things are extraordinarily dangerous to the heart and character of America.”

Romney added, “I think his comments time and again appeal to the racist tendency that exists in some people, and I think that’s very dangerous.”

On Friday, Romney closed his Facebook statement saying now was a “defining moment” for Trump.

“But much more than that, it is a moment that will define America in the hearts of our children,” he wrote. “They are watching, our soldiers are watching, the world is watching. Mr. President, act now for the good of the country.”

Other Republicans have lashed out against Trump for his remarks, as well.

On Tuesday, Sen. Marco Rubio, R-Fla., and a presidential hopeful in 2016, said white nationalists in Charlottesville were entirely at fault for the deadly violence in Charlottesville.

“The #WhiteSupremacy groups will see being assigned only 50% of blame as a win,” Rubio said on Twitter moments after Trump’s remarks. “We can not allow this old evil to be resurrected.”