Attorneys for President Trump on Monday told an accounting firm working for the president that it would be improper to turn over tax documents to a House committee that is expected to issue a subpoena for the material.

Last week, the chairman of the House Oversight Committee, Rep. Elijah E. Cummings (D-Md.), announced his intention to subpoena Mazars USA after the company refused a March request to hand over Trump’s financial documents, citing laws and rules that require a subpoena for such documents.

Cummings said the company had requested a “friendly subpoena” before it would comply with the request for information related to the Trump Organization, the president’s revocable trust and other entities.

On Monday, lawyers for the president and the Trump Organization wrote in a letter to the accounting firm’s counsel that a committee subpoena “would not be valid or enforceable.”

The president’s lawyers — William S. Consovoy and Stefan Passantino — wrote that a subpoena from Cummings’s panel would be invalid “because it would have no legitimate legislative purpose.”

They said that “the real reason that Chairman Cummings wants our clients’ financial information is to advance the Democrat Party’s agenda of politically attacking President Trump. . . . The Democrats’ fervor has only intensified after the Special Counsel squelched their ‘Russia collusion’ narrative.”

In a statement, Mazars USA said that the firm “believes strongly in the ethical and professional rules and regulations that govern our industry, our work and our client interactions.”

“As a matter of firm policy and professional rules we do not comment on the work we conduct for our clients,” the firm said. “Mazars USA will respect the legal process and fully comply with its legal obligations.”

Cummings did not immediately respond to a request for comment.

The pressure on the accounting firm to resist the looming House subpoena comes after the Treasury Department missed an initial deadline to hand over Trump’s tax returns to the House Ways and Means Committee, which then set another deadline of April 23.

Democrats in the House expect the Trump administration to take the battle over the tax returns to the courts, so they have sought other avenues to learn about Trump’s business practices.

The House panel told Mazars that it is seeking the documents to corroborate testimony of the president’s former lawyer, Michael Cohen, who told a congressional hearing recently that Trump artificially inflated and deflated the reported value of his assets for personal gain.

At the time of his testimony, Cohen gave the committee financial statements that he said Trump provided to Deutsche Bank during a 2014 attempt to buy the Buffalo Bills.

The documents showed Trump’s net worth soared from $4.55 billion in 2012 to $8.66 billion in 2013 because of the addition of a line item for $4 billion worth of “brand value”— essentially the value Trump placed on his name.

The Oversight Committee sent a letter to Mazars on March 20 requesting information on how those financial statements and other disclosure documents were prepared.

Consovoy and Passantino wrote Cummings on Monday that Mazars is required to decline the committee’s request “under federal law, New York law, and the ethical rules that govern accountants duties to their clients. Further attempts to obtain that information (by subpoena or otherwise) would be improper for many reasons.”