Rudolph W. Giuliani looks on before President Trump announces his Supreme Court nominee in the East Room of the White House on July 9, 2018. (Saul Loeb/AFP/Getty Images)

President Trump’s lawyer Rudolph W. Giuliani said Friday that congressional testimony by FBI agent Peter Strzok demonstrated such a bias against Trump that the results of the investigation being led by special prosecutor Robert S. Mueller III should be dismissed.

“Peter Strzok’s testimony was a disgrace,” Giuliani wrote in an early morning tweet. “It taints the entire Mueller witchunt. President Trump is being investigated by people who possess pathological hatred for him. All the results of the investigation are ‘fruit of the poison tree’ and should be dismissed.”

Giuliani’s assessment followed a heated day-long hearing Thursday that focused on the conduct of Strzok as the lead agent on FBI probes of Hillary Clinton and the Trump campaign, which Mueller is investigating for possible coordination with Russia during the 2016 election.

Strzok, a deputy assistant director at the FBI who oversaw counterintelligence cases, was removed from the Trump probe by Mueller in July 2017. At that time, investigators for the Justice Department inspector general discovered text messages between him and then-FBI lawyer Lisa Page in which they repeatedly disparaged Trump and expressed a strong desire that he not win the election.

During Thursday’s contentious hearing held by a pair of House committees, Republicans accused Strzok and the FBI of pursuing politically motivated probes aimed at harming Trump, while Democrats called the entire hearing part of a GOP attempt to protect the president by tainting the work of Mueller.

Strzok repeatedly said that his anti-Trump texts reflected his personal views, which he said did not affect his work.

Giuliani has sought on numerous occasions to undermine Mueller’s work by claiming that those who report to him are biased against Trump and calling them “angry Democrats.”

During a speech last month in Israel, for instance, Giuliani said that Mueller’s legal team is “trying very, very hard to frame” the president. During a television interview earlier this week, Giuliani said that if he were able to see the text messages of Mueller’s legal team, they would likely exhibit the same bias as those of Strzok and Page. He offered no evidence for that claim.

Mueller is a Republican who was appointed by deputy attorney general Rod J. Rosenstein, a Trump appointee who is also a Republican.

Devlin Barrett and Karoun Demirjian contributed to this report.