Treasury Secretary Steven Mnuchin again refused to release Donald Trump’s tax returns to House Democrats, arguing that the Democrats’ stated legislative purpose hides their real intent — to expose the president’s personal and business financial records to the public.

Mnuchin met House Ways and Means Committee Chairman Richard Neal’s Tuesday deadline to respond to his second request for the tax returns, but only by saying he would give a final response by May 6, when the Justice Department is expected to have completed its review of the request.

Neal, a Massachusetts Democrat, set an initial deadline of April 10 for Mnuchin and Internal Revenue Service Commissioner Charles Rettig to hand over six years of personal and business returns and then extended it to Tuesday when Mnuchin balked.

In a letter on Tuesday, Mnuchin said the request raised “serious constitutional questions” and that his department continued to consult with the Justice Department.

Neal’s request is “the culmination of a long-running, well-documented effort to expose the president’s tax returns for the sake of exposure,” Mnuchin wrote. Neal has said that the committee needs to see the returns to verify that the IRS is following its longstanding policy of auditing the president annually.

Mnuchin also cited public statements by House Speaker Nancy Pelosi, Neal and other Democratic leaders in which they suggested that the returns would be made public.

Neal responded in a statement Tuesday that he would consult with his legal counsel on his next steps.

House Democrats are locked in a political battle with the Treasury Department over whether Congress can legally obtain the president’s tax returns. Democrats say the law is on their side. The administration says the request is an illegal violation of Trump’s privacy.

The tax-return battle is just one front in Trump’s war against Democratic investigations of his conduct. On Monday, Trump and the Trump Organization asked a court to block a congressional subpoena seeking business records from his longtime accounting firm Mazars USA LLP.

Neal first asked for the tax returns on April 3, citing a 1924 law that allows the chairmen of the congressional tax committees to view the returns of any taxpayer. That request must be attached to a “legitimate legislative purpose,” so Neal cited oversight of IRS presidential audits.

House Democrats, Mnuchin wrote, believe they “need simply recite a legislative purpose, after which the department must ignore all evidence in the public record, however overwhelming, that the asserted purpose is pretext for a constitutionally suspect one.”

Trump broke with 40 years of presidential-campaign precedent when he refused to release his tax returns as a candidate. He said he was under audit and that he would consider releasing them when the audits were complete. No law prevents the release of tax returns that are under audit.

Earlier Tuesday, a White House spokesman said Trump is still “not inclined” to hand over the paperwork despite the deadline.

“The president is pretty clear. Once he’s out of audit, he will think about doing it. He’s not inclined to do so at this time,” White House Deputy Press Secretary Hogan Gidley told Fox News.

William Consovoy, one of Trump’s attorneys, has argued that Neal’s request doesn’t have a legitimate purpose and flouts fundamental constitutional constraints. Trump opposes the request.

Democrats want the returns to see if he has ties to foreign businesses and whether he cheated on his taxes. They also want to see if he benefited from his 2017 tax overhaul. Trump has said he is worth more than $10 billion. The Bloomberg Billionaire Index pegs his wealth at $2.8 billion.

Democrats are intensifying their probes into Trump’s behavior since the release of Special Counsel Robert Mueller’s report on April 18. On Monday, House Judiciary Committee Chairman Jerrold Nadler of New York subpoenaed former White House Counsel Don McGahn.

Earlier: Democrats Summon Ex-White House Lawyer McGahn on Mueller Report

McGahn, who spoke to investigators for about two dozen hours and appears more than 500 times in Mueller’s report, described Trump’s unrealized demands to aides to fire Mueller and pressure former Attorney General Jeff Sessions.

Mnuchin in Tuesday’s letter called Neal’s request “unprecedented” and said that fulfilling it could put taxpayer privacy at risk.