Senator John McCain (R-AZ) on Monday criticized President Donald Trump following his summit with Russian President Vladimir Putin, labeling Trump’s press conference with Putin as “one of the most disgraceful performances by an American president in memory.”

“President Trump proved not only unable, but unwilling to stand up to Putin,” McCain said in a statement.

“He and Putin seemed to be speaking from the same script as the president made a conscious choice to defend a tyrant against the fair questions of a free press, and to grant Putin an uncontested platform to spew propaganda and lies to the world,” added the veteran senator, who added that watching Trump’s press conference with Putin was especially “painful” after Trump criticized longtime NATO ally Germany as “totally controlled by Russia.”

“Coming close on the heels of President Trump’s bombastic and erratic conduct towards our closest friends and allies in Brussels and Britain, today’s press conference marks a recent low point in the history of the American presidency,” said McCain.

McCain, a longtime critic of Trump, on Friday suggested that Trump should cancel his meeting with Putin if he is not prepared to hold Putin "accountable" for aggression toward the U.S.

While McCain backed Trump in the presidential election in 2016, he previously said he has serious concerns about Trump, backing former Republican nominee Mitt Romney in his criticism.

In a memoir released in May, McCain accuses the President of failing to uphold U.S. values by showering praise on international "tyrants," discrediting the media, ignoring human rights and demeaning refugees.

McCain was joined on Monday by a host of other U.S. lawmakers, both Republican and Democratic, who criticized the Trump-Putin summit.

Republican Senator Lindsey Graham tweeted, “Missed opportunity by President Trump to firmly hold Russia accountable for 2016 meddling and deliver a strong warning ... This answer by President Trump will be seen by Russia as a sign of weakness and create far more problems than it solves.”

House of Representatives Democratic Leader Nancy Pelosi said in statement, “President Trump’s weakness in front of Putin was embarrassing, and proves that the Russians have something on the President, personally, financially or politically.”

Senate Republican Leader Mitch McConnell told reporters, “The Russians are not our friends and I entirely believe the assessment of our intelligence community.”

Senator Bob Corker, the Republican head of the U.S. Senate Foreign Relations Committee, said Trump’s comments at the joint news conference with Putin made the United States look like a “pushover.”

“When he had the opportunity to defend our intelligence agencies who work for him, I was very disappointed and saddened with the equivalency that he gave between them and what Putin was saying,” Corker told CNN in a reference to intelligence conclusions that Moscow interfered in the 2016 U.S. election and Putin’s denials that Republican Trump apparently accepted.

“The president’s comments made us look as a nation more like a pushover and I was disappointed in that,” he added.