House committees leading the impeachment inquiry against President Trump subpoenaed acting White House chief of staff Mick Mulvaney on Friday.

The big picture: This comes after nearly a month of White House refusals to comply with House investigations into whether Trump jeopardized national security by pressing Ukraine to interfere in the 2020 presidential election, and by withholding security assistance provided by Congress to help Ukraine, per the subpoena. The committees are demanding documents by Oct. 18.

"After nearly a month of stonewalling, it appears clear that the President has chosen the path of defiance, obstruction, and cover-up," the letter reads.

The state of play: Several White House officials have told Axios' Alayna Treene that the administration has no plans of complying with the committees' demands for interviews or documents without a full House vote formally approving an impeachment inquiry.

The big picture: The Trump administration's initial refusal to turn over the whistleblower complaint on the president's interactions with Ukraine is what led House Speaker Nancy Pelosi to finally support a formal impeachment inquiry.

Go deeper: Trump letter dares Pelosi to hold vote on impeachment inquiry