Testifying at the first public impeachment hearing on Wednesday, America’s top diplomat in Ukraine, Bill Taylor, laid out how an unofficial backchannel run by President Donald Trump’s personal attorney Rudy Giuliani “undercut” United States foreign policy as he offered up fresh information about Trump’s involvement in the plot.

Taylor, in a highly anticipated House Intelligence Committee hearing, told lawmakers of his objections to “holding up security assistance for domestic political gain,” referring to Trump’s apparent plan to make Ukrainian aid contingent on Ukrainian officials announcing an investigation into former Vice President Joe Biden, a political rival.

Taylor revealed for the first time that a staff member recently informed him that the staffer was at a restaurant with Ambassador to the European Union Gordon Sondland, a major Trump donor, when Sondland called Trump on July 26. During that call, the staff member said he could hear Trump ask about “the investigations,” an apparent reference to Trump’s desire for the Ukrainians to announced probes into Biden and his son. Sondland also told Trump the Ukrainians were ready to move forward, according to Taylor’s testimony.

“Following the call with President Trump, the member of my staff asked Ambassador Sondland what President Trump thought about Ukraine. Ambassador Sondland responded that President Trump cares more about the investigations of Biden, which Giuliani was pressing for,” Taylor testified.

Taylor’s testimony kicked off the public portion of the House impeachment inquiry, which will eventually move to the House Judiciary Committee and the full House. If the House votes to impeach Trump, the Republican-controlled Senate will decide whether to force Trump from office.

George Kent, a top State Department official who testified alongside Taylor, said it became clear to him in mid-August that “Giuliani’s efforts to gin up politically motivated investigations were now infecting US engagement with Ukraine”. 

Kent says Giuliani’s “smear campaign” against the former ambassador to Ukraine, Marie Yovanovitch, was “ubiquitous” on Fox News and online. Yovanovitch is set to testify on Friday.

Kent said he did not believe that the US “should engage in selective, politically associated investigations or prosecutions against opponents of those in power, because such selective actions undermine the rule of law regardless of the country”.

Taylor echoed his prior testimony in an October 22 closed-door session and spoke about how the official foreign policy of the United States “was undercut by the irregular efforts led by Mr Giuliani”. He told lawmakers that he thought it was “crazy” that the Trump administration was considering holding up assistance to Ukraine for political purposes.

Representative Devin Nunes (Republican), the ranking member of the House Intelligence Committee, accused Democrats of putting witnesses through a “closed-door audition process” to see which witnesses were ready for television. Republicans planned to argue that Democrats have been determined to impeach Trump since the moment he took office. 

Kent and Taylor were questioned for 45 minutes by Democratic staffer Daniel Goldman and for 45 minutes by Republican staffer Stephen Castor. Lawmakers on the committee questioned both officials in the afternoon.

Republicans complained at the hearing that neither Kent nor Taylor had any firsthand knowledge of the president’s actions and described their testimony as hearsay. 

Representative Mark Meadows (Republican), one of Trump’s top defenders on Capitol Hill, told reporters after the hearing that, although he thought both men were “credible public servants”, their testimony was “not credible because it’s not based on firsthand knowledge”.

The White House, of course, has blocked many primary witnesses from testifying at the same time they’ve complained there aren’t any firsthand witnesses. When HuffPost asked if Meadows would tell Trump that the White House should cooperate with the investigation so individuals with firsthand knowledge could testify, Meadows demurred.

“I don’t know that the president’s going to pay attention to what this member from North Carolina may or may not say,” Meadows replied with a smile.