Donald TrumpDonald John TrumpArizona GOP Senate candidate defends bus tour with far-right activist Alyssa Milano protests Kavanaugh in 'Handmaid's Tale' costume Bomb in deadly Yemen school bus attack was manufactured by US firm: report MORE said on Sunday that Mitt Romney lost the presidential race in 2012 because of his tax returns.

"He waited 'til September to give 'em, just before the election. They made him look so bad. It was so unfair," Trump said of the GOP's 2012 presidential nominee on ABC's "This Week."

"I actually think he didn't lose because of the 47 percent [comments]. I think he lost because of a couple of really minor items in a tax return, where he did nothing wrong. ... It is unfair."

Trump, this year's GOP nominee, reiterated that he will release his tax returns after the Internal Revenue Service completes an audit, even though the agency has said he can make them public while an audit is underway.

Host George Stephanopoulos pushed back, saying past returns that aren't being audited could be released.

"Yeah, but they're all linked," Trump said. "It's called the link. If my audit's finished, that's great."

Last week, Trump's campaign chief, Paul Manafort, said Trump "will not be releasing" his taxes.

"Mr. Trump has said that his taxes are under audit and he will not be releasing them. It has nothing to do with Russia. It has nothing to do with any country other than the United States and his normal tax auditing process."