Mitt Romney

WASHINGTON — Former Republican presidential nominee Mitt Romney charged into the increasingly divisive 2016 GOP White House sweepstakes today with a harsh takedown of front-runner Donald Trump, calling him a “phony” and exhorting fellow Republicans to shun him for the good of the country and party.

“His promises are as worthless as a degree from Trump University,” Romney said in a speech readied for delivery to a University of Utah audience. In turning up the rhetoric, Romney cast his lot with a growing chorus of anxious Republican leaders — people many Trump supporters view as establishment figures — in trying to slow the New York real estate mogul’s momentum.

“Here’s what I know: Donald Trump is a phony, a fraud,” Romney said in his talk, set for delivery later today.

Trump, in turn, disparaged Romney in a series of tweets: “I am not a Mitt Romney, who doesn’t know how to win,” “Romney, who ran one of the worst races in presidential history, is working with the establishment to bury a big ‘R’ win!” and Romney is “not a good messenger” to be telling Republicans how to get elected.

Romney has been chipping away at Trump in recent days, but the speech today was certain to be his most forceful statement yet. Trump has responded to Romney by saying the former Massachusetts governor was a failed candidate in his own right.

Panicked GOP leaders say they still have options for preventing the billionaire from winning the GOP nomination — just not many good ones. Romney also declares that a Trump nomination at the party’s convention in Cleveland in July would enable Democrat Hillary Clinton to win the presidency, according to excerpts of his speech obtained by The Associated Press.

He charged that Trump “has neither the temperament nor the judgment to be president.”

Romney’s involvement comes as party elites pore over complicated delegate math, outlining hazy scenarios for a contested convention and even flirting with the long-shot prospect of a third party option.

The 2012 Republican nominee’s speech marks his most aggressive step into the 2016 contest to date, but it was unclear what impact his words would have with voters deeply frustrated by their party’s leaders.

Trump, meanwhile, was setting his sights on the general election. His campaign reached out to House Speaker Paul Ryan’s office to arrange a conversation between the two men, and urged Republican leaders to view his candidacy as a chance to expand the party.

“Why can’t the leaders of the Republican Party see that I am bringing in new voters by the millions — we are creating a larger, stronger party!” Trump said on Twitter.

Indeed, there was a surge in turnout in Super Tuesday’s GOP primaries. While that could typically be a welcome sign for a party that has struggled to attract new voters, GOP leaders were privately grappling with the reality that some of those voters were in fact registering their opposition to the Republican establishment.

Trump padded his lead with victories in seven Super Tuesday contests, with Texas Sen. Ted Cruz claiming three states and Florida Sen. Marco Rubio picking up his first victory of the 2016 race.