Romney takes aim at Trump over taxes, The Donald fires back

Mitt Romney and Donald Trump mixed it up Wednesday after the former Republican nominee for the White House faulted the New York billionaire – currently the GOP's leading presidential contender – for not making public his tax returns.
Trump's resistance to releasing his tax returns suggests there may be a "bombshell" waiting to go off when he does, Romney speculated in an interview with Fox News host Neil Cavuto.