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President Donald Trump continues to hold his ground against Democratic efforts to obtain his tax returns, with one administration official telling CNN that the President and his team are willing to fight the House Democratic request all the way to the Supreme Court.

“This is a hill and people would be willing to die on it,” the official said.

House Ways and Means Committee Chairman Richard Neal formally requested six years of Trump’s personal tax returns from the Internal Revenue Service in a letter Wednesday.

The official added that the administration is “not going to set the precedent” of turning over tax returns for future occupants of the Oval Office, slamming the House Democrat request from Neal as “abuse and overreach by Congress” and asked what’s stopping Senate Republicans from seeking House Speaker Nancy Pelosi’s returns.

“They have zero right to it,” the official said, who added Trump has also made it clear he’s not releasing his tax returns.

READ: Trump lawyers send letter pushing back on tax return request

Trump has retained Arlington, Virginia-based law firm Consovoy McCarthy Park PLLC to represent him on the matter.

Lawyer William Consovoy argued in a statement on Friday that the requests for Trump’s tax information “are not consistent with governing law, do not advance any proper legislative purpose, and threaten to interfere with the ordinary conduct of audits.”

In the Wednesday request, Neal cited a little-known IRS code. 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.

But in a detailed letter to the general counsel of the Treasury Department on Friday, Consovoy said that “the committee’s authority is subject to important constraints,” which, he said, citing the tax code, “extend to the ordinary taxpayer and the President alike.”

Consovoy said that Neal does not have a “legitimate committee purpose” for obtaining the tax returns, adding that Neal’s request “is a transparent effort by one political party to harass an official from the other party because they dislike his politics and speech.”

Trump’s attorneys have been preparing for several months to beat back an anticipated request for the President’s tax returns, a source close to Trump’s legal team tells CNN.

“We’ve been looking at this issue for several months,” the source said.

“it’s not just a tax issue,” the source added. “In fact it’s really not a tax issue, it’s really a statutory and constitutional issue.”

After Democrats won the House, it became clear that they would try and use the little known provision of the tax code to request Trump’s tax returns from the IRS. Trump’s attorneys wanted to be ready to go for when Neal decided to pull the trigger on his request.

The President and his legal team decided to entrust the case to Consovoy and his firm in part because he had already been representing the President in the emoluments case.

“This is not a new team member,” the source points out.

The Democrats’ request was also rebuked by congressional Republicans, with House Republican Leader Kevin McCarthy warning Thursday that it “sets a dangerous standard of having the federal government used as a political weapon” and dismissing the move as “a waste of time.”

Trump himself sidestepped a question Thursday afternoon over whether he will tell the commissioner of the IRS to not comply with the congressional request for his tax returns.

“They’ll speak to my lawyers and they’ll speak to the attorney general,” Trump told reporters from the Oval Office.

And on Friday, when asked if he was confident he would be able to keep the Democrats from obtaining his taxes, Trump told reporters: “Oh, I don’t know. That’s up to whoever handles it. I don’t know. Hey, I’m under audit. But that’s up to whoever it is. From what I understand, the law is 100% on my side.”

The IRS has yet to respond to the request, which is likely to trigger months or even years of legal battles. The likely next step would be that the Treasury Department would get opinions on how to handle the matter, which could involve the Justice Department’s Office of Legal Counsel.

“We will see you in court,” the administration official said.