The former Massachusetts governor posted on Facebook
Friday that he will support Cruz in Utah, where Romney currently resides. Romney did not use the word "endorsement," and he has personally encouraged Republicans to engage in what is called
"strategic voting" in which they cast ballots for the GOP candidate most likely to stop Donald Trump in their respective state.
"This week, in the Utah nominating caucus, I will vote for Senator Ted Cruz," he wrote, saying that no candidate besides Trump can win before a convention -- which Cruz himself disagrees with. "The only path that remains to nominate a Republican rather than Mr. Trump is to have an open convention. At this stage, the only way we can reach an open convention is for Senator Cruz to be successful in as many of the remaining nominating elections as possible."
Romney, perhaps the country's most prominent Mormon politician, could give Cruz a boost in Utah's caucuses, where Mormons form a majority of the state's population and the candidate is scheduled to campaign this weekend. On Friday, Cruz told a local radio host that he had a "significant lead" over Trump.
Romney maintained that he had respect for Ohio Gov. John Kasich, the only other remaining GOP candidate and with whom he has campaigned. Cruz's Utah state chairman, Phill Wright, said after Romney's backing early Friday morning that Cruz had no plans to campaign with Romney in the state.
"I would have voted for him in Ohio. But a vote for Governor Kasich in future contests makes it extremely likely that Trumpism would prevail," Romney said.
On the campaign trail, Cruz has had often very harsh words for Romney, dubbing him a seriously flawed messenger against Barack Obama in 2012 and characterizing him as part of the GOP's "mushy middle" repeatedly in his stump speech.
But he quickly thanked Romney
for the support in a tweet Friday afternoon. Asked at a news conference on the Arizona-Mexico border later Friday why anti-Trump Republicans such as Romney had not offered full-fledged endorsements, Cruz said Romney's vote was sufficient.
"I'll take that, and take that happily," Cruz told reporters.
Other campaigns reacted less kindly: A few minutes after Romney made his news, Kasich's chief strategist, John Weaver, tweeted
: "Good to know Ted Cruz is the establishment, K-Street backed candidate. #HelloStatusQuo."
Later Friday, Kasich's campaign released a new web ad in Utah that highlighted when Romney stumped for him in Ohio.
And Trump, who has been even harsher toward Romney than Cruz has, said the former Massachusetts governor's support for Cruz was good for his campaign.
"Failed presidential candidate Mitt Romney, the man who 'choked' and let us all down, is now endorsing Lyin' Ted Cruz. This is good for me!" he tweeted
He added, "Going to Salt Lake City, Utah, for a big rally. Lyin' Ted Cruz should not be allowed to win there - Mormons don't like LIARS! I beat Hillary."