Mitt Romney rips Trump for not releasing his taxes: He can only be hiding 'bombshell of unusual size'

Former Republican presidential candidate Mitt Romney blasted the party's current presumptive nominee, Donald Trump, on Wednesday for his reticence to release his tax returns.

"There is only one logical explanation for Mr. Trump's refusal to release his returns: there is a bombshell in them," Romney wrote on his Facebook page. "Given Mr. Trump's equanimity with other flaws in his history, we can only assume it's a bombshell of unusual size."

Romney, the former governor of Massachusetts, said it was "disqualifying" for Trump to hold off on making his tax returns public, given that he has not been vetted like a typical candidate or military service member would.

"Tax returns provide the public with its sole confirmation of the veracity of a candidate's representations regarding charities, priorities, wealth, tax conformance, and conflicts of interest," Romney wrote. "Further, while not a likely circumstance, the potential for hidden inappropriate associations with foreign entities, criminal organizations, or other unsavory groups is simply too great a risk to ignore for someone who is seeking to become commander-in-chief."

The real estate magnate has said that he would not release his tax returns until after the election, citing the fact that he is being audited.

But the Internal Revenue Service has already rebutted the claim, saying that an audit would have no effect on doing so. It also questioned Trump's allegation that he has been audited for multiple consecutive years, calling it "rare."

Romney, who lost in his attempt to stop President Barack Obama's re-election in 2012, argued in his post that Trump could also release tax returns from the years preceding his audit.