Democrats in the U.S. House of Representatives have issued three more subpoenas to U.S. officials as part of their impeachment inquiry of President Donald Trump.

The House committees leading the impeachment investigation demanded to hear testimony from Ulrich Brechbuhl, a key aide to Secretary of State Mike Pompeo, as well as two officials in the White House’s Office of Management and Budget: acting Director Russell Vought and Associate Director for National Security Programs Michael Duffey. 

FILE – President Donald Trump meets with Ukrainian President Volodymyr Zelenskiy at the InterContinental New York Barclay hotel during the U.N. General Assembly, Sept. 25, 2019, in New York.

House Democrats are probing Trump’s efforts to seek Ukraine’s help to investigate a political rival, Joe Biden, and his son, Hunter Biden. A whistleblower report that launched the impeachment investigation said Brechbuhl listened in on a July phone call between Trump and Ukrainian President Volodymyr Zelenskiy in which Trump pressed for the investigation, using U.S. aid to Ukraine as leverage.

The Trump administration has sought to block administration officials from appearing before lawmakers conducting the impeachment inquiry.

Also Friday, a U.S. judge granted a request by House Democrats to access information blacked out of former special counsel Robert Mueller’s report on his investigation of Russian interference in the 2016 U.S. election.

The ruling by Chief U.S. District Judge Beryl Howell in Washington was a victory for House Democrats, who had been seeking the redacted documents as part of their impeachment investigation.

FILE – House Republicans speak to reporters after Deputy Assistant Defense Secretary Laura Cooper arrived to testify at a closed-door deposition as part of the impeachment inquiry into President Donald Trump, Oct. 23, 2019.

Earlier this week, Republican lawmakers barged into a closed-door impeachment proceeding, delaying testimony for five hours. 

Republicans demanded the release of transcripts of testimony from multiple diplomatic and national security officials, many of whom provided information about the pressure Trump exerted on Ukraine to open investigations into the Bidens. 

The White House said Trump was “very supportive” of the Republican lawmakers’ actions. 

Trump has denied there was a quid pro quo in his overtures to Ukraine and described his July call to the Ukrainian president as “perfect.”  

FILE – White House Acting Chief of Staff Mick Mulvaney speaks during a press briefing at the White House in Washington, Oct. 17, 2019.

Last week, the president’s acting chief of staff, Mick Mulvaney, told reporters that attaching strings to U.S. aid — a quid pro quo — was nothing new and that the news media should “get over it.” 

House Intelligence Committee Chairman Adam Schiff of California has said impeachment inquiry transcripts eventually will be released, while officials say public impeachment hearings could start as soon as mid-November. 

If the House votes to impeach Trump, he would face a trial in the Republican-led Senate, where it remains unlikely that a two-thirds majority would vote to convict Trump and remove him from office.