House Ways and Means Committee Chairman Richard Neal made clear Saturday that Democrats in the House of Representatives are not giving up on their demand to see President Donald Trump’s tax returns. Neal reiterated his demand for Trump’s tax returns, telling IRS Commissioner Chuck Rettig in a letter that he has until April 23 to turn over the files. The move amounts to a rebuke of Treasury Secretary Steve Mnuchin, who had said he wasn’t even sure that Neal had the authority to make the request in the first place.

“I expect a reply from the IRS by 5:00 p.m. on April 23, 2019. Please know that if you fail to comply, your failure will be interpreted as a denial of my request,” Neal wrote in the letter that came days after Mnuchin said there was no way the administration could meet the original April 10 deadline. In the letter, Neal pushed back against Mnuchin’s questions about whether lawmakers had the oversight authority to make what the treasury secretary had characterized as “unprecedented” request. “The Committee’s request raises serious issues concerning the constitutional scope of Congressional investigative authority, the legitimacy of the asserted legislative purpose, and the constitutional rights of American citizens,” Mnuchin wrote. “The legal implications of this request could affect protections for all Americans against politically-motivated disclosures of personal tax information, regardless of which party is in power.”

Neal said he wasn’t buying that rationale. “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.

The hard deadline aspect of Neal’s letter is significant because it seems inevitable the request will turn into a long legal battle. If the administration denied the request then that could set the stage for a subpoena or a lawsuit. So far though, no one has denied the request outright. Neal also spells out in the letter why the request “falls squarely within the Committee’s oversight authority” and said that any questions of the motives behind the demand for documents were unacceptable. “It is not the proper function of the IRS, Treasury, or Justice to question or second guess the motivations of the Committee or its reasonable determinations regarding its need for the requested tax returns and return information,” Neal wrote.