Report: Romney tapes phone message for Rubio’s campaign

Mitt Romney is lending Marco RubioMarco RubioWill Republicans stand up to the NRA's insurrection rhetoric? The Hill's Whip List: Senate ObamaCare repeal bill Ivanka Trump turns to House GOP on paid family leave MORE his voice with a phone recording airing in the four states conducting GOP presidential contests on Tuesday.

“[Vote for] a candidate who can defeat Hillary ClintonHillary Rodham ClintonAre Democrats trying to pin the blame for their own sins on Russia? Trump: Calling Warren Pocahontas ‘an insult to Pocahontas’ GOP vows to use Pelosi against Democrats in 2018 MORE and who can make us proud,” the 2012 GOP nominee said in the message, according to The New York Times.

“If we Republicans were to choose Donald TrumpDonald TrumpShould government 'outsource' censorship to Facebook and Twitter? Sanders: FBI's investigation of wife won’t be a ‘distraction’ Schiff: Obama's delayed response to Russian interference 'a very serious mistake' MORE as our nominee, I believe that the prospects for a safe and prosperous future would be greatly diminished — and I’m convinced Donald Trump would lose to Hillary Clinton.”

Romney stops short of formally endorsing Rubio’s Oval Office bid in the clip, the Times reported late Monday evening.

It also said the Florida senator’s presidential campaign is sending the call to likely voters in Idaho, Hawaii, Michigan and Mississippi.

Romney’s message may resonate most in Idaho, the Times said, where many Republican primary voters are Mormon like the 2012 GOP presidential nominee. It may additionally help Rubio in Michigan, where Romney's father, George Romney, was governor from 1963 to 1969.

Romney has become one of Trump’s fiercest critics, arguing that the billionaire’s policy stances and temperament disqualify him from the presidency.

He offered his most stinging criticism last Friday, vowing he would never vote for Trump should the real estate tycoon take the Republican presidential nomination.

Rubio, meanwhile, is scrambling to reverse his campaign’s momentum after a series of disappointing results nationwide. He won only two such events since last month, well behind Trump’s 12 and six for Sen. Ted CruzTed CruzSenate Republicans reluctant to rush vote on healthcare bill Healthcare bill 'not the last step' to repealing ObamaCare, Republican says Dem senator: GOP's healthcare approach will 'devastate Medicaid' MORE (R-Texas).

Trump remains the GOP presidential front-runner nationwide, leading his rivals by nearly 16 points in the latest RealClearPolitics average of polls.