Former Republican presidential candidate Mitt Romney hasn't endorsed a 2016 candidate yet, but has taken the stage to cast doubt on candidate Donald Trump.
In an appearance at Babson College in Wellesley, Mass., and in a Fox News interview, Romney repeatedly mentioned the need for voters to see candidates' past taxes.
In an interview with Neil Cavuto on Fox News' "Your World," Romney said that, if released, there would be a "bombshell" in Trumps tax returns.
"Either he's not anywhere near as wealthy as he says he is, or he hasn't been paying the kind of taxes we would expect him to pay," Romney said in the interview.
Romney said the issue of tax returns was a sticking point in his campaign, which is "why I'm so sensitive to it."
Former Senate Majority Leader Harry Reid called for Romney's taxes on the Senate floor during the 2012 presidential election.
Reid noted the irony of the situation to CNN, according to a CNN article.
"All I know, I can't imagine Romney having the gall coming after anybody's returns," Reid said in the article.
The discourse escalated Thursday in a series of Tweets exchanged between Trump and Romney.
Trump called Romney a dope and "one of the dumbest and worst candidates" in GOP history and tweeted that he was "going to do what @MittRomney was totally unable to do- WIN!"
Mitt Romney, who was one of the dumbest and worst candidates in the history of Republican politics, is now pushing me on tax returns. Dope!— Donald J. Trump (@realDonaldTrump) February 25, 2016
Just for your info, tax returns have 0 to do w/ net worth. I have already filed my financial statements w/ FEC. They are great!— Donald J. Trump (@realDonaldTrump) February 25, 2016
Romney pushed back, tweeting his spin on William Shakespeare:
According to Washington Post National political reporter David Weigel in a video and Cavuto, "Trump is leading in literally every Super Tuesday state except Texas" and has double-digit leads in more than half of the Super Tuesday states.
In the Fox News interview, Romney said Trump was most likely to be the GOP candidate, although it was "not impossible but very difficult" for another candidate to emerge.
"Well, I think there's no question that Donald Trump has the clearest path to become the Republican nominee," Romney said in the interview. "I think for the other people stuck in the race their path is becoming a slimmer and slimmer opening and they're having a difficult time communicating to their supporters just how they could become the nominee."
Weigel said other GOP contenders would have less to work with as Super Tuesday draws closer.
"The only thing you have really is a debate and those are possibly the least predictable factors in this race in terms of how they affect Donald Trump," Weigel said in the video.
At Babson College, Romney said the current political climate came from a nation that was "mad as hell and won't take it anymore," according to a Washington Post article.
"Certainly part of what is behind the energy and the passion for Donald Trump on the Republican side and Bernie Sanders on the Democratic side is the frustration and anger people feel in this country," Romney said.