U.S. Ambassador to the European Union Gordon Sondland told Congress an effort to push Ukraine to investigate former Vice President Joe Biden and his son would not only be "improper" but likely illegal.

In his testimony, a transcript of which was released Tuesday, Sondland says that it "would be improper" for Rudy Giuliani, Trump's personal lawyer, to push Ukraine to investigate Biden and his son or involve Ukrainians in the 2020 presidential election. When asked if this would also be illegal, Sondland suggests it would be.

"I'm not a lawyer, but I assume so," he responded, adding of Giuliani's effort to investigate Burisma, the gas company where Biden's son served on the board, "it doesn't sound good." Sondland also says at another point in the testimony that "I would not endorse investigating the Bidens."

This testimony came as part of the House of Representatives' impeachment inquiry into President Trump, which is examining whether the president withheld aid to Ukraine in order to secure investigations that might benefit him politically. Sondland revised previous testimony to reveal that he did tell a Ukrainian official that "resumption of the U.S. aid would likely not occur until Ukraine provided the public anticorruption statement that we had been discussing for many weeks."

Sondland claims he "did not understand until much later" that Giuliani's agenda "might have" included an attempt to involve Ukraine in the 2020 election, and The Washington Post notes that "Sondland's main defense has been that, while he did push for an investigation into the company that employed Joe Biden's son Hunter Biden, Burisma Holdings, he didn't know the situation involved the Bidens." At the same time, Kurt Volker, former special envoy to Ukraine, in his testimony suggested Burisma for Trump was probably synonymous with Biden, notes CBS' Steven Portnoy, with Volker saying Trump "would not know or even know how to pronounce or be familiar with the name of a company like that." Brendan Morrow