He also asserted that leadership in the State Department, the National Security Council and the White House were all well aware of what was going on with Ukraine.
The poll also found that those who reported they are following the hearings closely are almost twice as likely to say that the president requested an investigation from the Ukrainians, 61 percent to 34 percent. "He has violated his oath of office".
The California Democrat says lawmakers involved in the House impeachment inquiry haven't decided what charges they might bring against Trump.
Sondland also testified it was his understanding the president held up almost $400 million in military aid to Ukraine to pressure Zelensky into announcing the investigations.
Trump has denied any wrongdoing or a "quid pro quo", calling the inquiry a "new hoax".
Vindman contrasted the public impeachment hearings, where government officials are testifying openly against President Trump, with authoritarian governments around the world where dissent is not tolerated. The Republican-controlled Senate would then hold a trial on whether to remove him from office, although few Republican senators have been critical of Trump so far.
51% of those asked said they think Trump should be tried and convicted in the US Senate, while another 6% favour impeachment but not removal, according to the ABC News-Ipsos poll released Monday.
"We aren't finished yet, the day is not over", Pelosi said during her weekly press conference.
She again issued an invitation to Trump to come forward, saying, "if you have any information that is exculpatory. because it seems as if the facts are uncontested to what happened".