The 2016 U.S. Presidential Elections is fast approaching. And as the campaign period intensifies, former presidential hopeful Mitt Romney urges Republican nominees to release their tax return, putting emphasis on Donald Trump.

Romney, a former Massachusetts governor and 2012 GOP presidential nominee, has called on Trump on Wednesday to release his tax returns. As a matter of fact, he speculated that the GOP frontrunner in the 2016 race could have a "bombshell" on his taxes.

Romney vs. Trump

"We have good reason to believe that there's a bombshell in Donald Trump's taxes," Romney said during his interview with Fox News host Neil Cavuto on Wednesday.

Romney also added that Trump may not be as wealthy as how Americans have perceived him to be.

"Well, I think there's something there. 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 added. "Or perhaps he hasn't been giving money to the vets or the disabled, like he's been telling us he's been doing."

In addition, Romney also questioned Trump's donations on several charities. He said that it would be a major issue if the tax returns show that the business tycoon has not made any contributions to the disabled veterans.

Romney vs. Cruz and Rubio

Aside from Trump, Romney also urged other Republican presidential hopefuls including Senators Marco Rubio and Ted Cruz to release their tax returns.

"We're now in late February and we still haven't seen Donald Trump's or Marco Rubio's or Ted Cruz's taxes," Romney added.

He also challenged the Republican presidential hopefuls that if they don't want transparency on their taxes, it would simply mean that there's something they don't want the public to see.

Trump's Remarks

Donald Trump, on the other hand, declined to comment on Romney's remarks. But after the interview, the real estate mogul took to Twitter, criticizing Romney as "playing a tough guy."

"Mitt Romney, who totally blew an election that should have been won and whose tax returns made him look like a fool, is now playing tough guy," Trump posted on Twitter.

Trump has also stressed that his accountants have been comprehensively going through his tax returns. Unfortunately, it would take some time since his tax returns are "complicated" and "massive."

Romney's Statements

Meanwhile, Romney's statements didn't actually came as a surprise since he has long been known as one of Trump's critics. And his statements came after he was asked about his endorsement in the 2016 U.S. Presidential Elections during the public discussions on Wednesday.