As a presidential candidate, Trump broke with the tradition followed by most candidates since Richard Nixon by refusing to release his tax returns. Trump had promised to release the documents following the completion of an audit — a status that fact-checkers have concluded does not bar him from disclosing them .

But while the legal path to obtaining and publicly sharing Trump's coveted tax filings may be relatively straightforward, some of the president's supporters have already vowed to resist such a request from Democrats. That refusal could set up an unprecedented legal battle between lawmakers and the Trump administration.

A decades-old law could soon give Democrats their best shot yet at extracting President Donald Trump 's tax returns from the Internal Revenue Service.

Two days after his inauguration, senior advisor Kellyanne Conway said Trump is "not going to release his tax returns" because "people didn't care." More recently, he insisted that his returns are too complex for people to understand.

When Democrats gain majority control of the House of Representatives on Thursday, they will also take over the top slots on the various House committees. That includes the House Ways and Means Committee, which carries the legal authority to make a formal request to obtain years of Trump's tax returns.

A provision in a Calvin Coolidge-era tax law allows Ways and Means, as well as the Senate Finance Committee and the Joint Committee on Taxation, to send a written request enjoining the Treasury secretary to fetch any individual's returns from the IRS.

The documents would then be delivered for committee members to view in a confidential setting. From there, the committee could publicly release the returns, according to University of Virginia law professor George Yin.

As the minority party, Democrats made more than a dozen failed attempts to obtain Trump's tax returns through the 1924 provision, which was added with the then-brewing Teapot Dome investigation in mind. With a majority in the House, Democrats will have the power to back up their demands.

"The new Democratic House will be dedicated to conducting actual oversight of an executive awash in corruption. That oversight begins with Trump's tax returns, which absurdly to this moment haven't seen the light of day," said Rep. Bill Pascrell, D-N.J., who has led the charge in pursuit of Trump's returns.

With Republicans maintaining control of the Senate Finance Committee, all eyes have turned to Ways and Means Chairman-designate Rep. Richard Neal, D-Mass., to submit that written request.

Neal has already said "Yes, I think we will" ask for Trump's tax returns when he takes control of the committee.

If the administration refuses to comply, Neal told the Associated Press, "Then I assume that there would be a court case that would go on for a period of time."

Once the request is sent to the Treasury chief — in this case, Steven Mnuchin — the text of the law itself appears to provide little wiggle room to object. That law says the Treasury secretary "shall furnish" the documents to the committee members requesting them.

"From my perspective, this should be relatively cut and dried," said David Kamin, a professor specializing in tax and budget policy at the New York University School of Law.