Treasury Secretary Steven Mnuchin told House Ways and Means Chairman Richard E. Neal Monday that the IRS will not hand over President Donald Trump’s tax returns and associated information.

“In reliance on the advice of the Department of Justice, I have determined that the Committee’s request lacks a legitimate legislative purpose, and … the Department is therefore not authorized to disclose the requested returns and return information,” Mnuchin wrote in a letter to Neal.

In an April 23 letter to Neal, Mnuchin had written that he had asked for an opinion from the Justice Department and would make a determination by May 6 as to whether he would comply with Neal’s request.

Mnuchin informed Neal that the Justice Department “has informed us that it intends to memorialize its advice in a published legal opinion as soon as practicable.” Mnuchin wrote that he was therefore informing Neal that the Treasury Department “may not lawfully fulfill the Committee’s request.”

“Today, Secretary Mnuchin notified me that the IRS will not provide the documents I requested under Section 6103 of the Internal Revenue Code. I will consult with counsel and determine the appropriate response,” Neal said in a statement.

The Massachusetts Democrat has a number of options. Hecould make another request — his third since April 3 — and set a new deadline, file a lawsuit in federal court, or issue a subpoena. If a subpoena is issued and Mnuchin continues to refuse to turn over the records, Neal could appeal to a court to enforce the subpoena or seek a contempt of Congress vote on the House floor.

Neal’s request has been made under Sec. 6103 of the tax code, which states that upon “written request” from the chairman of either of the two tax-writing committees, “the Secretary shall furnish such committee with any return or return information specified” in the request.

Experts tend to side with Neal, since the plain language of the 1924 statute appears clear. Not only is there “no wiggle room” in the statue’s “shall furnish” and “any return” language, the legislative history of the law appears to be on Neal’s side as well, said George K. Yin, a professor at the University of Virginia School of Law and former chief of staff of the Joint Committee on Taxation.

When the law was written 95 years ago, it was clear that Congress was granting itself what at the time was the same unconditional authority to get tax information from the IRS as the president already had, Yin has said.

Meanwhile, every president since Richard M. Nixon has released his tax returns in an exercise that had become a pro forma part of presidential contests. While Trump has been criticized for not releasing his returns voluntarily, experts point out that there is no law requiring him to do so.

If a subpoena were issued, failure to comply also could lead to Mnuchin being held in contempt of Congress, along with a court order of daily fines or even jail until he does comply, experts, including Yin, have said.

Mnuchin and Neal have been playing tag over the issue for more than a month since Neal on April 3 made his first written request for six years of Trump’s individual tax returns. He also asked whether any individual return is or has been under audit, why it was selected for audit and the IRS’ administrative files, including work papers and affidavits concerning the returns. And Neal asked for the same information covering six years of returns for eight Trump businesses.

Although both of Neal’s letters have been addressed to IRS Commissioner Charles Rettig, who Democrats argue has been delegated authority by the Treasury Secretary for all IRS administrative matters, it has been Mnuchin who has responded.

In his April 3 letter, Neal set an April 10 deadline for compliance.  Mnuchin responded on that date that he couldn’t respond in the amount of time given, that he would review the request carefully and suggested that the request “raises serious issues” about Congress’ investigative authority, the constitutional rights of citizens and whether Neal had a sufficient legislative purpose for requesting Trump’s returns.

Three days later, Neal sent his second letter, setting a new deadline of April 23, while rejecting Mnuchin’s concerns and asserting that the request for Trump’s returns “falls squarely within the Committee’s oversight authority.”

On April 23, calling Neal’s request “unprecedented,” Mnuchin said he needed time to consult with the Justice Department and would respond by May 6.

While Neal hasn’t indicated what his next step will be, a senior Democrat on House Ways and Means speculated last week about how the chairman would react to Mnuchin’s expected rejection.

“He hasn’t said this to me, but I think he’ll try the third letter and it will be the final letter,” Rep. Bill Pascrell Jr., D-N.J., told reporters when asked to forecast how Neal would react to a rejection.

“And then, don’t be surprised if we move towards contempt of the Congress,” he said, noting the process for that path would involve the expiration of a final deadline, followed by a subpoena.

Watch: Trump: ‘We’re fighting all the subpoenas’