The House of Representatives will vote to formalize its procedures for the impeachment of President Trump sometime this week, Speaker Nancy Pelosi said Monday.

The White House has refused to cooperate with the probe, arguing in part that the inquiry is invalid because the full House did not vote to authorize it. The House voted to open the impeachments of Presidents Nixon and Clinton.

Though all but a small handful of House Democrats have publicly said they support the probe, Pelosi has held off until now, arguing that there is no constitutional requirement to hold a vote. The House is investigating whether Trump abused his powers by urging Ukraine to investigate a political rival, former Vice President Joe Biden.

In a letter to colleagues on Monday, Pelosi said she would bring a resolution that “affirms the ongoing existing investigation” now being conducted by House committees. The resolution will also set up a procedure for public hearings and the release of deposition transcripts.

Pelosi said the procedures would afford “due process rights to the President and his Counsel.”

“We are taking this step to eliminate any doubt as to whether the Trump Administration may withhold documents, prevent witness testimony, disregard duly authorized subpoenas, or continue obstructing the House of Representatives,” Pelosi said. “Nobody is above the law.”

Trump’s lawyer, Rudy Giuliani, has said he will not comply with subpoenas, citing the White House counsel’s contention that the probe is invalid. Vice President Mike Pence has also resisted a request to provide evidence on the same grounds.