Gordon Sondland had been due to meet behind closed doors with staff of three Democratic-led House committees over the role he may have played in President Trump's efforts to get Ukraine to probe former vice president Joe Biden, a political rival.
President Donald Trump attacked the Democratic lawmaker Adam Schiff spearheading the impeachment inquiry on Monday as congressional committees subpoenaed his personal lawyer, Rudy Giuliani, for documents related to his dealings with Ukraine.