Treasury Secretary Steve Mnuchin sent a letter to House Ways and Means Chairman Richard Neal (D-Mass.) Tuesday informing him that the Treasury Department will decide by May 6 whether to release President Trump's tax returns to Congress — effectively ignoring the April 23 deadline that Neal had set."Due to the serious constitutional questions raised by this request and the serious consequences that a resolution of those questions could have for taxpayer privacy, the Department is consulting with the Department of Justice. Although federal law establishes no deadline for a response to your request, we expect to provide the Committee with a final decision by May 6, after receiving the Justice Department's legal conclusions."The big picture: In the past few days, the Trump administration has taken a number of steps to block oversight by House Democrats, or — as the president and his defenders have labeled it — "presidential harassment."On Monday, Trump and the Trump Organization sued House Oversight Chairman Elijah Cummings in an attempt to block Cummings' subpoena of Trump's longtime accountant, Mazars USA LLP.Also on Monday, White House directed former security clearance official Carl Kline not to comply with an Oversight subpoena. Cummings is now moving to hold Kline in contempt of Congress.And as the Washington Post reported Tuesday, the administration also plans on fighting a House Judiciary subpoena of former White House counsel Don McGahn.