Mitt Romney says he will vote for Texas Senator Ted Cruz in Utah caucus as he is “repulsed” by Donald Trump.

The former Republican presidential candidate said in a Facebook post that the only way to nominate a Republican is to have an open convention, in which party officials choose the nominee.

Mitt Romney campaigned with Governor John Kasich in Ohio but said voting for Ted Cruz is the only way to stop “Trumpism”.

He joins other Republican leaders coalescing around Ted Cruz.

Donald Trump has won the most state contests and holds 678 delegates – 1,237 are needed to win the nomination.

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“Mitt Romney is a mixed up man who doesn’t have a clue. No wonder he lost!” Donald Trump said on Twitter.

However, Republican leaders are concerned that Donald Trump’s controversial comments about immigrants, women and Muslims would make him a weak candidate in the general election in November.

Some also feel that the onetime Democrat cannot be trusted to implement conservative policies.

“Today, there is a contest between Trumpism and Republicanism,” Mitt Romney said.

“Through the calculated statements of its leader, Trumpism has become associated with racism, misogyny, bigotry, xenophobia, vulgarity and, most recently, threats and violence. I am repulsed by each and every one of these.”

Earlier this month, Mitt Romney gave a speech outlining why he was against Donald Trump, a billionaire businessman with no political experience, calling him a “phoney” and a “fraud”.

Mitt Romney’s home state of Utah holds its presidential contest on March 22.

A group of conservatives including well-known talk radio host Erick Erickson met on March 17 to discuss ways to defeat Donald Trump, including launching a third party campaign to challenge the New York businessman.

“We encourage all former Republican candidates not currently supporting Trump to unite against him and encourage all candidates to hold their delegates on the first ballot,” he said in a statement, put out on behalf of the group.

“We believe that the issue of Donald Trump is greater than an issue of party. It is an issue of morals and character that all Americans, not just those of us in the conservative movement, must confront.”

Many GOP members have also misgiving about Ted Cruz because he has repeatedly and publicly denounced Republican leaders.

However, more prominent Republicans are throwing their support behind Ted Cruz in a last-ditch effort to stop Donald Trump.

Popular South Carolina Governor Nikki Haley and Senators Mike Lee of Utah and Lindsey Graham of South Carolina have recently endorsed Ted Cruz.

Florida Senator Marco Rubio, who left the Republican race on March 15, said this week he would not be endorsing any of his former rivals.

He also said he had no interest in becoming a vice-presidential nominee.

Donald Trump won four out five primaries on March 15, but the race in Missouri has not been called for the Republicans yet.

Hillary Clinton narrowly won the state’s Democratic primary after her opponent Vermont Senator Bernie Sanders declined to pursue a recount.