DETROIT (Reuters) - Former Republican U.S. presidential nominee Mitt Romney gave a blistering rebuke of 2016 party front-runner Donald Trump on Thursday, the latest sign of how badly mainstream figures in the party want to stop the incendiary New York billionaire.
Romney, an elder statesman in the party, urged Republicans in states that have not yet held nominating contests to vote for Trump's opponents to stop his march to the nomination for the Nov. 8 election to succeed President Barack Obama.
"Here's what I know. Donald Trump is a phony, a fraud," said Romney, 68, who has kept a low profile since losing to Obama in 2012.
"He's playing the members of the American public for suckers. He gets a free ride to the White House and all we get is a lousy hat," he said.
Trump has made his party's establishment uneasy with his positions on trade and immigration, including his calls to build a wall between the United States and Mexico, deport 11 million illegal immigrants and temporarily bar Muslims from entering the country.
Romney pointed to the billionaire real estate developer's refusal to release his tax returns and initial reluctance to disavow an endorsement from a former leader of the Ku Klux Klan white supremacist group.
Romney, who did not endorse anyone, suggested Republicans vote for candidates who appear poised to do the best against Trump in states still to hold nominating votes: Senator Marco Rubio in Florida, Ohio Governor Kasich in his home state, and Senator Ted Cruz from Texas where he is strong.
Romney said Trump's economic policy would sink America "into prolonged recession" and his foreign policy would endanger the country. He criticized his business acumen and his temperament.
"This is the very brand of anger that has led other nations into the abyss," he said.
Ahead of the speech, much of which had been previewed in excerpts, Trump dismissed Romney in television interviews and posts on Twitter, calling him "a failed candidate" who had "begged" him for an endorsement in 2012.
"Mitt Romney is a stiff," Trump told NBC's "Today" program.
Romney's strategy risks backfiring by further energizing Trump's supporters, who are angry with a party they see as not defending their interests.
"If you’re Trump, this is like getting the good kind of Kryptonite," Republican strategist Doug Heye said.
Romney's speech came hours before Trump and rivals Marco Rubio, Ted Cruz and John Kasich share a debate stage in Detroit.
It risks locking Trump's opponents out of news coverage until the 9 p.m. EST (0200 GMT Friday) debate hosted by Fox News begins. The debate will be the candidates' first face-to-face gathering since Super Tuesday nominating contests this week gave extra momentum to Trump but did not knock out his rivals.
Additional reporting by Susan Heavey, Megan Cassella, Eric Beech, James Oliphant; Writing by Steve Holland and Roberta Rampton; Editing by Peter Cooney, Lisa Von Ahn and Alistair Bell