Governor Mitt Romney called Republican presidential candidate Donald Trump “a phony and a fraud” Thursday morning and asked the Republican Party to support the other GOP candidates.

“His promises are as worthless as a degree from Trump University,” Romney said in his speech held at the University of Utah. “He’s playing the American public for suckers. He gets a free ride to the White House, and all we get is a lousy hat.”

Romney said it is a time for choosing for the Republican Party and electing Donald Trump would be harmful for the future of the U.S.

‘‘The only serious policy proposals that deal with the broad range of national challenges we confront today, come from Ted Cruz, Marco Rubio and John Kasich,’’ Romney said. ‘‘One of these men should be our nominee.’’

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Romney has not endorsed any candidate in the 2016 election.

“On the other hand, if we make improvident choices, the bright horizon I foresee will never materialize,” Romney said. “Let me put it plainly: if we Republicans choose Donald Trump as our nominee, the prospects for a safe and prosperous future are greatly diminished.”

Romney said Trump’s economic proposals would be harmful to American workers and families and that the U.S. would fall into a national recession.

“Now I know you say, ‘Isn’t he a huge business success, and doesn’t he know what he’s talking about?’ No he isn’t, and no he doesn’t,” Romney said. “His bankruptcies have crushed small businesses and their workers. He inherited his business; he didn’t create it.”

Romney also said Trump’s domestic and foreign policies will alarm our allies and fuel the enmity of our enemies.

“He creates scapegoats of Muslims and Mexican immigrants,” Romney said. “He calls for use of torture and killing the innocent children and families of terrorists. He cheers assaults on protesters. He applauds the prospect of twisting the Constitution to limit First Amendment freedom of the press. This is the very brand of anger that has led other nations into the abyss.”

Sen. John McCain commented on Romney’s speech Thursday morning.

“I share the concerns about Donald Trump that my friend and former Republican nominee, Mitt Romney, described in his speech today,” McCain said in a statement. “I would also echo the many concerns about Mr. Trump’s uninformed and indeed dangerous statements on national security issues that have been raised by 65 Republican defense and foreign policy leaders.”

Romney said he understands the anger Americans face today and that in the past, former presidents have channeled that anger into resolutions and will to defeat enemies of freedom. He said Trump is something different.

“His domestic policies would lead to recession,” Romney said. “His foreign policies would make America and the world less safe. He has neither the temperament nor the judgment to be president. And his personal qualities would mean that America would cease to be a shining city on a hill.”