"I'm being audited now for two or three years, so I can't [release the returns] until the audit is finished, obviously," Trump said during CNN's Republican debate Thursday night. "And I think people would understand that."
Trump suggested to CNN after the debate that he was being targeted by the IRS because of his faith.
"Well, maybe because of the fact that I'm a strong Christian, and I feel strongly about it, maybe there's a bias," he said. "You've had many religious groups complaining about it, they've been complaining about that for a long time."
The billionaire businessman's claim comes after Mitt Romney said earlier this week that Trump's tax returns could contain a "bombshell" that voters deserve to know about. "Either he's not anywhere near as wealthy as he says he is, or he hasn't been paying taxes we would expect him to pay or perhaps he hasn't been giving money to vets or to the disabled like he's been telling us he's been doing," Romney said on Fox News Wednesday.
After the debate Romney tweeted that the audits shouldn't stop Trump from releasing his tax returns.
"@realDonaldTrump taxes for last 4+ years are still being audited. There are more #bombshells or he would release them," he said.
Trump fired back at Romney in a series of tweets Thursday:
"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!"
"Just for your info, tax returns have 0 to do w/ someone's net worth," he added in another tweet. "I have already filed my financial statements w/ FEC. They are great!"
But Romney was not so easily put off. "Methinks the Donald doth protest too much. Show voters your back taxes, @realDonaldTrump. #WhatIsHeHiding," Romney tweeted back.
As one Twitter user suggested, maybe this is "what [Trump] gets for hiring 2 Corinthians to prep his taxes."