WASHINGTON – Treasury Secretary Steven Mnuchin said he would not release President Donald Trump's tax returns on Tuesday, missing the second deadline set by Congress for the department to hand over the documents, and instead said his department would offer a final decision on the matter by May 6.

In a five-page letter to Ways and Means Committee chairman Richard Neal, which was followed by five pages of public statements by Democrats about the president's taxes, Mnuchin outlined his concerns over releasing six years of the president's tax returns and said the delay was due to waiting on guidance from the Justice Department.

"History demonstrates that private tax return information is susceptible to abuse for partisan purposes — regardless of which party is in power," Mnuchin wrote in the letter. "Unless carefully restrained by law, this risk threatens the privacy of all taxpayers."

Mnuchin detailed both the constitutional concerns and his department's worries with releasing the president's financial information and accused Democrats of attempting to skirt the law in order to obtain the documents, something they have been after since even before Trump was elected.

Rep. Neal, D-Mass., made the original request for Trump's tax returns to the IRS, which is housed under the Treasury Department, on April 3. He invoked a law allowing a select few members of Congress to review individual tax returns for legislative purposes and cited legislative proposals and oversight related to Federal tax laws as his reasoning behind the request.

It was the first such demand for a sitting president’s tax information in 45 years.

"I plan to consult with counsel about my next steps," Neal said in response to Mnuchin's Tuesday letter.

Neal is one of only three congressional officials authorized under the 1924 law to make a written request to the treasury secretary for anyone’s tax returns. The law says the treasury secretary “shall furnish” the requested material to members of the committee for them to examine behind closed doors.

Trump was the first president in modern history who did not release his tax returns, citing an ongoing audit.

"Your request presents the question whether there are any legal limits on the ability of a Congressional tax-writing committee to obtain an individual's private tax returns from the IRS and disclose them publicly," Mnuchin wrote in his Tuesday letter to Neal.

Mnuchin said the committee appeared to believe that all they needed was to "recite a legislative purpose" and Treasury Department should hand over the request, and "ignore all evidence in the public record, however overwhelming, that the asserted purpose is pretext for a constitutionally suspect one."

Earlier Tuesday, the White House said it had no plans to release the returns. Spokesman Hogan Gidley told Fox News that, "the president is pretty clear, once he’s out of audit, he’ll think about doing it, but he is not inclined to do so at this time."

Gidley emphasized that Trump was elected president, despite not releasing his tax returns.

"No one cares about ridiculous charges about tax returns and all types of other things that Democrats are doubling down on today," he said.

Neal first sent a letter to IRS Commissioner Charles Rettig on April 3, demanding copies of Trump's taxes from 2013 through 2018. He gave Rettig about a week to comply with the demand., Rettig did not meet that deadline. Neal gave an extension, until April 23 at 5 p.m.

Rettig also sent a letter to Neal Tuesday, referring to the Treasury Department's letter and explaining that the IRS had yet to make a decision over whether to release Trump's tax returns. Rettig said he was waiting on guidance from the Justice Department.

"I am aware that concerns have been raised regarding my request and the authority of the Committee. Those concerns lack merit. Moreover, judicial precedent commands that none of the concerns raised can legitimately be used to deny the Committee’s request," Neal wrote to Rettig on April 13.

"If you fail to comply, your failure will be interpreted as a denial of my request," he continued in the letter.

Acting White House chief of staff Mick Mulvaney told Fox on April 7 that Democrats will "never" see the returns.

Democrats have tried to get their hands on Trump's tax returns since he flouted tradition and refused to release them during his presidential campaign. When he took office, Trump continued to keep them private.

Before the 2018 election, Rep. Nancy Pelosi, D-Calif., told the San Francisco Chronicle's editorial board that requesting Trump's tax returns “is one of the first things we’d do – that’s the easiest thing in the world. That’s nothing."

Comments made by Pelosi, Neal and other Democrats were noted in Mnuchin's Tuesday letter, in an attempt to question the committee's motives.

Neal, the only person in the House who can request the returns, took his time before issuing the demand. His spokeswoman, Erin Hatch, said Neal expected the request would end up in a legal battle, so the Massachusetts Democrat was building a case.

In the Senate, Finance Committee Chair Chuck Grassley, R-Iowa, has the ability to make the request, but he said he is not interested in requesting the tax returns. He said he views Neal's request as a political stunt, but if the House Democrats receive them, he will make the request for parity

"When you strip out all their pretexts, and when you strip out their circular logic, all you have are Democrats who want to go after the president any way they can. They dislike him with a passion, and they want his tax returns to destroy him. That’s all this is about, and it’s Nixonian to the core," Grassley said on the Senate floor after Neal made the initial request.

Monday, Trump and his private business filed a federal lawsuit to block the House Committee on Oversight and Reform from obtaining financial records from the company’s longtime accountant.

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Contributing: William Cumming and Bart Jansen