Report: Romney tapes phone message for Rubio’s campaign

Mitt Romney is lending Marco RubioMarco Antonio RubioStudents gather outside White House after walkout to protest gun violence Overnight Energy: Senate confirms Bridenstine as NASA chief | Watchdog probes Pruitt’s use of security detail | Emails shine light on EPA science policy changes Senate confirms Trump’s pick to lead NASA 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 Diane Rodham ClintonGeorge HW Bush wears 'book socks' to Barbara Bush's funeral to honor her passion for literacy Obamas, Clintons to attend funeral of Barbara Bush Hillary Clinton to fundraise in DC for public charter high school 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 John TrumpFlynn to campaign for Montana GOP Senate candidate Trump considering pardon for boxing legend after call from Sylvester Stallone Decline in EPA enforcement won't keep climate bill from coming 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 CruzRafael (Ted) Edward CruzCruz's Dem challenger slams Time piece praising Trump Race for Republican Speaker rare chance to unify party for election 32 male senators back Senate women's calls to change harassment rules 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.