House Judiciary Committee Chairman Jerrold Nadler, who is planning a vote to hold former White House counsel Don McGahn in contempt of Congress, issued new subpoenas Tuesday for McGahn aide Annie Donaldson and former White House communications director Hope Hicks.

“As I said earlier today, the Judiciary Committee’s investigation into obstruction of justice, public corruption and abuse of power by President Trump and his Administration will continue,” Nadler, D-N.Y., said in a statement.

“I have issued these subpoenas today to two critical witnesses who have worked closely with the President. We are seeking the information in order to conduct proper oversight, consider potential legislation and perform our constitutional duties.”

McGahn, on orders from the Justice Department, ignored a subpoena to appear before the Judiciary panel Tuesday and Nadler is now threatening to cite him with contempt.

According to Nadler, Donaldson, who served as McGahn’s chief of staff, and Hicks, were “critical witnesses,” to “alarming misconduct and obstruction of justice,” by President Trump, which Nadler said are documented in special counsel Robert Mueller’s report on Russian interference in the 2016 election.

Nadler sent both Hicks and Donaldson document requests in March.

The subpoena calls on Donaldson to turn over documents by June 4 and to testify on June 24. The subpoena compels Hicks to turn over documents on June 4 and to testify on June 19.

The Judiciary Committee hasn’t had much luck forcing Trump’s aides to testify or turn over documents, and the stalemate has led to progressive Democrats calling for impeachment proceedings, which they believe will give them access to more of the material and testimony they seek.

The panel voted to cite Attorney General William Barr with contempt of Congress after he failed to turn over the unredacted Mueller report, even though the law compels him not to release the redactions.