A Democratic House chairman on Saturday castigated the Treasury Department for failing to meet his deadline to furnish President Trump’s tax returns, arguing that the administration’s apparent concerns over his use of powers outlined in the Internal Revenue Service’s tax code “lack merit.”

The chairman, Representative Richard E. Neal, Democrat of Massachusetts, set a new deadline for compliance, April 23, and warned that if the Trump administration did not reply by then, its “failure will be interpreted as a denial of my request.”

The tone of Mr. Neal’s letter suggested Democrats are prepared to take their request — made through a little-known provision in the federal tax code — to court if necessary, initiating what could be a protracted legal fight over Congress’s oversight powers. In it, he cited legal precedent that he argued clearly showed the law is on the committee’s side, and said that the executive branch had no right to “second guess” its motivations.

[Read the letter here.]

“I am aware that concerns have been raised regarding my request and the authority of the committee,” Mr. Neal wrote. “Those concerns lack merit. Moreover, judicial precedent commands that none of the concerns raised can legitimately be used to deny the committee’s request.”