Washington (CNN) Congressional Democrats will "never" obtain President Donald Trump's tax returns, acting White House chief of staff Mick Mulvaney said Sunday.

"Nor should they (obtain the documents)" Mulvaney told "Fox News Sunday." "Keep in mind, that's an issue that was already litigated during the election. Voters knew the President could have given over his tax returns, they knew that he didn't and they elected him anyway. Which, of course, is what drives the Democrats crazy."

Mulvaney's comments come several days after House Ways and Means Committee Chairman Richard Neal, a Democrat from Massachusetts, formally requested six years of Trump's personal tax returns from the Internal Revenue Service.

In a letter sent Wednesday to the IRS, Neal cites a little known IRS code in his request for six years of Trump's personal tax returns from 2013 to 2018. He also requested the tax returns of eight of Trump's business entities, a nod to escalating pressure from liberals in the caucus who have argued that Trump's personal returns wouldn't sufficiently paint a picture of the President's financial history.

"The Democrats are demanding that the IRS turn over the documents and that is not going to happen and they know it," Mulvaney told Hemmer, adding that the request "is a political stunt."

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