A top House Democrat on Friday issued subpoenas for six years of Donald Trump’s tax returns, giving the treasury secretary, Steven Mnuchin, and the IRS commissioner, Charles Rettig, a deadline of next Friday to deliver them.

Richard Neal, the chairman of the House ways and means committee, issued the subpoenas days after Mnuchin refused to comply with demands to turn over Trump’s returns. Mnuchin told the panel he wouldn’t provide Trump’s tax records because the panel’s request “lacks a legitimate legislative purpose”, as supreme court precedent requires.

Neal reminded the two Trump appointees in a Friday letter that federal law states that the IRS “shall furnish” the tax returns of any individual upon the request of the chairmen of Congress’s tax-writing committees, and that ways and means “has never been denied” a request.

The White House and the Democratic-controlled House are waging a multi-front battle over investigations into Trump, with the administration refusing to comply with subpoenas for the unredacted Mueller report and documents related to testimony by the former White House counsel Donald McGahn.

If Mnuchin and Rettig refuse to comply with the subpoenas, Neal is likely to file a lawsuit in federal court. He indicated earlier this week that he was leaning toward filing a court case immediately but changed course after meeting with lawyers for the House.

Neal originally demanded access to Trump’s tax returns in early April. He maintains that the committee is looking into the effectiveness of mandatory IRS audits of tax returns of all sitting presidents, a way to justify his claim that the panel has a potential legislative purpose. Democrats are confident in their legal justification and say Trump is stalling in an attempt to punt the issue past the 2020 election.

In rejecting Neal’s request earlier this week, Mnuchin said he relied on the advice of the justice department. He concluded that the treasury department was “not authorized to disclose the requested returns and return information”. Mnuchin has also said that Neal’s request would potentially weaponize private tax returns for political purposes.

Republicans say Neal is using the arcane 1924 law that empowers him to obtain any individual’s tax filing to play politics with Trump. Democrats also want to investigate Trump’s business dealings, particularly his business relationships with foreigners and to see who he owes money to.

“Your request is merely a means to access and make public the tax returns of a single individual for purely political purposes,” said the ways and means panel’s top Republican, Kevin Brady.

In a statement, Neal said: “While I do not take this step lightly, I believe this action gives us the best opportunity to succeed and obtain the requested material.”

Trump has privately made clear he has no intention of turning over the much coveted records. He is the first president since the Watergate scandal to decline to make his tax returns public. Trump has linked the effort to the myriad House investigations into his administration and has urged his team to stonewall all requests. He also has inquired about the “loyalty” of the top officials at the IRS, according to one of his advisers.

Trump has often claimed that he would release the returns if he were not under audit. But in recent weeks, he has added to the argument, telling advisers that the American people elected him once without seeing his taxes and would do so again, according to the three officials, who spoke on condition of anonymity.

