(CNN) House Ways and Means Committee Chairman Richard Neal has formally requested President Donald Trump's tax returns from the Internal Revenue Service, likely launching a battle with the administration that could stretch months or even years in the courts and could shed light on the President's finances.

Trump said late Wednesday that he wouldn't be inclined to provide his tax returns to Congress until he was no longer under audit.

Asked about the request for six years of his tax returns, Trump asked, "Is that all? Oh, usually it's 10 so I guess they're giving up."

"Now, we're under audit, despite what people said. We're working that out as -- I'm always under audit it seems. But I've been under audit because the numbers are big and I guess when you have a name you're audited. But until such time as I'm not under audit I would not be inclined to do that," he added during a White House meeting with military leaders.

While the move will largely be seen by Republicans as a political escalation, Neal explained in the letter the request is part of his oversight role. Neal wrote that the committee needed Trump's tax returns to consider legislation related to the IRS's practice of auditing sitting presidents.

"Under the Internal Revenue Manual, individual income tax returns of a President are subject to mandatory examination, but this practice is IRS policy and not codified in the Federal tax laws," Neal wrote in a letter to the IRS. "It is necessary for the committee to determine the scope of any such examination and whether it includes a review of underlying business activities required to be reported on the individual income tax return."

In a statement to CNN, Neal stressed that the committee's request was about "policy, not politics."

"My preparations were made on my own track and timeline, entirely independent of other activities in Congress and the administration," Neal said. "My actions reflect an abiding reverence for our democracy and our institutions, and are in no way based on emotion of the moment or partisanship. I trust that in this spirit, the IRS will comply with federal law and furnish me with the requested documents in a timely manner."

Neal has given the IRS until April 10 to comply with the request.

A months-long debate

Neal's announcement follows a months-long debate within the Ways and Means Committee about how and when to issue the request for Trump's tax returns.

Unlike other sensitive material Democratic chairmen have demanded from the Trump administration, the request for Trump's tax returns could only come from one Democrat on Capitol Hill. Under IRS code 6103, only the Joint Committee on Taxation, the House Ways and Means chairman and the Senate Finance Committee chairman have the authority to request the tax information of an individual. Given the Senate Finance Committee Chuck Grassley has long said requesting Trump's tax returns would be akin to weaponizing the tax-writing committee, the ask fell to Neal.

But, behind the scenes, Neal was meticulous about the decision. Democrats believe the statute is clear. Under the code, it says "the secretary shall furnish such committee with any return or return information specified in such request." But, Neal, a pragmatic and judicious chairman more interested in working with the administration on shared priorities like infrastructure then launching a contentious, partisan fight that could define his tenure, proceeded cautiously.

"I am certain we are within our legitimate legislative, legal and oversight rights," Neal said in his statement Wednesday.

Liberals on the committee pressured Neal both publicly and behind closed doors. Rep. Bill Pascrell, a Democrat from New Jersey, announced at the beginning of March that Neal was going to request Trump's tax returns in two weeks only to backtrack hours later to clarify it was only his opinion, not official guidance. Democratic Rep. Lloyd Doggett, a member of Ways and Means lamented that it was past time for Neal to make the request for days leading up to the request.

Members also wanted Neal to expand any request to be not just personal returns, but also business returns. And in their sweeping ethics reform legislation H.R. 1, Democrats included a provision that would require presidential nominees and sitting President's to disclose 10 years of business returns.

Ultimately, Neal requested information from eight of Trump's business entities including the Bedminster golf course LLC as well as the Donald J. Trump Revocable Trust, DJT Holdings LLC, DJT Holdings Managing Member LLC, DTTM Operations LLC, DTTM Operations Managing Member Cor, LFB Acquisition Member Corp, and LFB Acquisition LLC.

In the early days of his chairmanship, Neal focused on building a relationship with members of the Trump administration including Treasury Secretary Steve Mnuchin. Even when Mnuchin refused to appear before his committee for a hearing on the impact of the government shutdown on the upcoming tax season, the two men continued to work in coordination. Neal told CNN in March that he'd spoken directly with the President about his goals for infrastructure.

When Mnuchin did appear before his committee on March 14, Neal's opening statement reflected a chairman more interested in working with the administration on infrastructure and pension restoration than a liberal Democrat preparing to request the President's most closely-held personal documents related to his income and business practices over the last few years.

Ultimately, Neal made his request to the Internal Revenue Service, not Treasury, which Mnuchin heads. During that committee hearing where Mnuchin testified, he signaled to the committee that he has not handled other 6103 requests in the past.

When asked by a committee member about this, Mnuchin responded, "That is not something I would normally sign. It would be something that the IRS commissioner would sign off on."

While Democratic chairmen across the Capitol want to see Trump's tax returns for their own investigations, Neal's formal request is specific and targeted: an investigation into a program that audits the taxes of sitting presidents. Under 6103, only Neal -- not the chairman of other committees-- will be provided the information.

"The IRS has a policy of auditing the tax returns of all sitting presidents and vice presidents, yet little is known about the effectiveness of this program," Neal said in a statement.

This story has been updated with additional developments Wednesday.