WASHINGTON Testifying at the first public impeachment hearing Wednesday, Americas top diplomat in Ukraine, Bill Taylor, laid out how an unofficial backchannel run by President Donald Trumps personal attorney Rudy Giuliani undercut United States foreign policy as he offered up fresh information about Trumps 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 Trumps 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 Trumps 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 Taylors 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.

Taylors 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.