The chairman of the House Ways and Means Committee has formally asked the Internal Revenue Service to hand over six years of President Trump’s tax returns, setting up what is expected to be a vicious court battle with the Trump administration as the president faces mounting scrutiny over his finances.

In a letter to IRS Commissioner Charles Rettig, Rep. Richard Neal (D-MA) reportedly requested the agency hand over Trump’s “personal and business” tax returns from 2013 to 2018. The New York Times reports that Neal also requested returns from Trump’s trust and seven of Trump’s “core” businesses that have control of other “operations”—including his Bedminster, New Jersey, golf course. On top of all that, Neal asked the agency to share any other information it had on those entities, including their audit history.

While Trump told reporters after the news broke that he “would not be inclined” to comply with the request, the obscure tax provision used to submit it leaves little room for his legal team to weasel out of it.

IRS Code statute 6103, which gives the authority to “tax-writing committees in Congress” to request information on any tax filer, is not believed to have been used in the past to view the tax returns of a president.

But it does give the House Ways and Means Committee “statutory authority” to subpoena Trump’s tax returns, and there’s no reason why the IRS would not be compelled to hand them over in this case, Martin Sheil, a retired Supervisory Special Agent for the IRS, told The Daily Beast.

“I don't know of anything off the top of my head that would prevent the IRS from disclosing the Trump tax returns under a properly written request by a duly authorized authority,” Sheil said, noting, however, that Trump and his legal team will almost certainly put up a fight.

“President Trump has very good attorneys and they have been put on notice since the 2018 elections that the tax return request will likely be coming. So they will try to slow down the process and attempt to make it a long drawn out court battle,” he said.

The IRS has until April 10 to comply with the request.

In a statement, Neal said the request was based on “policy, not politics[.]”

“We have completed the necessary groundwork for a request of this magnitude and I am certain we are within our legitimate legislative, legal, and oversight rights,” he wrote. “I trust that in this spirit, the I.R.S. will comply with federal law and furnish me with the requested documents in a timely manner.”

Trump—who is the first president in almost 50 years not to release his tax returns voluntarily—largely shrugged off the news and claimed that he was already “under audit.”

“Is that all? Well, usually its ten [years] so I guess they’re giving up,” Trump told reporters Wednesday afternoon. “We are under audit, despite what people said, and working that out… I'm always under audit, it seems, but I've been under audit for many years 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 it."

Trump's lawyer, Rudy Giuliani, told The Daily Beast that the committee's action showed they have “no concern of constitutional or legal boundaries.”

“Even rabid Dem Congress can’t invade the privacy of our tax returns. The IRS not partisan politicians investigate taxes,” he wrote. “Isn’t this what Nixon was accused of doing to his political foes. Why the media double standard?”

The political mudslinging began almost immediately after Neal’s request to the IRS. Rep. Kevin Brady (R-TX) submitted his own letter to Treasury Secretary Steve Mnuchin on Wednesday, calling Neal’s request the “latest effort” in their “misguided rash to impeach President Trump” and an “abuse” of the committee’s authority.

“Weaponizing our nation’s tax code by targeting political foes sets a dangerous precedent and weakens Americans privacy right,” Brady wrote. “When Congress violates the rights of one taxpayer for political purposes, it begins the process of eroding and threatening the privacy rights of all taxpayers.”

Mnuchin told the committee last month they would protect Trump’s privacy if Congress submitted the request for the tax returns, NBC News reports.

“I have discussed with the legal department in the Treasury that we will most likely receive this request,” Mnuchin said at the time. “As I have said, based upon the request we'll examine it and we will follow the law… and we will protect the president as we would protect any individual taxpayer under their rights.”

Another congressional committee, House Oversight and Reform Committee, is also requesting Trump’s financial information. Rep. Elijah Cummings (D-MD) said earlier Wednesday that tax and accounting firm Mazars USA was prepared to turn over a decade of Trump’s financial records if they received a subpoena from the committee.

“They have told us that they will provide the information pretty much when they have a subpoena,” Cummings told reporters, according to Politico. “And we’ll get them a subpoena.”