For indispensable reporting on the coronavirus crisis, the election, and more, subscribe to the Mother Jones Daily newsletter.

A top House Democrat stepped up the heat on Saturday in the fight for access to President Donald Trump’s tax returns, demanding that the IRS hand over the documents to members of Congress by a late April deadline.

Rep. Richard Neal, chairman of the House Ways and Means Committee, first made the request on April 3 for six years of Trump’s personal and business taxes, information that could shed light on the president’s business dealings and potential conflicts of interest. The Trump administration quickly pushed back: It hired a team of lawyers to focus on the issue, and told the IRS it needed more time to consider Neal’s request.

“It is not the proper function of the IRS, Treasury, or Justice to question or second guess the motivation of the Committee…regarding its need for the requested tax returns and return information.”

On Saturday, Neal sent a letter to IRS Commissioner Charles Rettig, arguing that a 1924 law clearly gives Congress the right to see Trump’s taxes. He set a hard deadline of April 23 for the agency to comply with his request. “It is not the proper function of the IRS, Treasury, or Justice to question or second guess the motivation of the Committee or its reasonable determination regarding its need for the requested tax returns and return information,” Neal wrote.

The Trump administration missed a previous April 10 deadline to share these documents, and the White House has said they will “never” be turned over. Trump has argued in the past that he could not reveal his tax returns to the public because he was under a routine audit, though being under audit does not legally prevent these documents from being released. “I am aware that concerns have been raised regarding my request and the authority of the Committee,” Neal wrote in his letter to the IRS commissioner. “Those concerns lack merit.”

If the tax returns are not given to lawmakers by April 23, it appears increasingly likely the showdown could head to federal court, the Associated Press reports. Neal could also attempt to subpoena the documents.

Meanwhile, Democratic lawmakers in statehouses are pushing for the president’s tax information via a different channel. On Monday, two Democrats in New York, Trump’s home state, said they planned to introduce a bill that would make it easier for the state to hand over tax returns to congressional committees. On Thursday, the Illinois state Senate advanced legislation that would require Trump to release five years of his returns in order to put his name on the state’s 2020 presidential ballot. Seventeen other states are reportedly considering similar legislation.