US President Donald Trump’s questioning on Monday of American intelligence conclusions that Russia had interfered in the 2016 presidential election sparked a wave of criticism from Republicans and Democrats alike. Speaking at a summit with his Russian counterpart Vladimir Putin, Trump said he had been told by his CIA chief that Moscow was to blame, but he was not certain. “I don’t see any reason why it would be” Russia, Trump said. “President Putin was extremely strong and powerful in his denial today.” That came three days after the US Justice Department indicted 12 Russians for hacking Democratic Party computers, the latest in a series of actions taken by the US government since late 2016 in retribution for what intelligence agencies say was a broad plan to support Trumps election campaign directed by Putin himself. Trump also appeared to embrace Putins offer to have Russian investigators work together with US prosecutors on the case of the 12 just indicted. "I think thats an incredible offer." The reaction back home was swift. Republican Senator John McCain called it "one of the most disgraceful performances by an American president in memory." He said the Helsinki summit was a “tragic mistake” and “Trump “failed to defend all that makes us who we are - a republic of free people dedicated to the cause of liberty at home and abroad.” House Speaker Paul Ryan, the top Republican in Congress, said Russia undoubtedly interfered in the 2016 election. “The president must appreciate that Russia is not our ally. There is no moral equivalence between the United States and Russia, which remains hostile to our most basic values and ideals,” he said in a statement. Senate Foreign Relations Committee Chairman Bob Corker, a Republican, said Trump’s comments next to Putin made the United States look like a “pushover.” Republic Senator Lindsey Graham, a sometime Trump ally, tweeted that it was a "bad day for the US." He said the summit was a “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.” "This is shameful," said Senator Jeff Flake, a fellow Republican and staunch critic of the president. "I never thought I would see the day when our American president would stand on the stage with the Russian president and place blame on the United States for Russian aggression." Director of National Intelligence Dan Coats, a Republican and a Trump appointee, responded to Trump’s remarks and stood by the US agencies. “We have been clear in our assessments of Russian meddling in the 2016 election and their ongoing, pervasive efforts to undermine our democracy,” Coats said. John Brennan, who served as CIA director, called Trumps comments "treasonous." "Donald Trumps press conference performance in Helsinki rises to & exceeds the threshold of high crimes & misdemeanors. It was nothing short of treasonous. Not only were Trumps comments imbecilic, he is wholly in the pocket of Putin. Republican Patriots: Where are you???" he tweeted. The language used by Democrats was much harsher. House Minority Leader Democratic Nancy Pelosi said Trumps weakness in front of Putin wasnt just "embarrassing" but also "proves that the Russians have something on the President, personally, financially or politically." Democratic California Representative Jimmy Gomez charged: "To side with Putin over US intelligence is disgusting; to fail to defend the US is on the verge of treason." Democratic Senator Chuck Schumer said never in the history of the country has an American president supported an adversary the way Trump sided with Putin. “For the president of the United States to side with President Putin against American law enforcement, American defense officials, and American intelligence agencies is thoughtless, dangerous, and weak,” he added. He challenged Republicans to move beyond words and confront the president directly by increasing sanctions on Russia and requesting testimony about the summit from Trump administration officials, among other things. "We need our Republican colleagues to stand up for the good of this country," he said. Former Vice President Joe Biden, a Democrat, weighed in after the summit. “Flattering dictators will not advance American interests. It makes us less safe,” Biden said of Trump’s remarks. At least one Republican, Senator Rand Paul of Kentucky, scoffed at both parties "beating their chests" on Russia and "dumbing down" the debate, saying its important for the US to have diplomatic channels open with its adversaries if the country hopes to change behavior. "Theyre making a big mistake," Paul said. He dismissed the presidents critics as those who hate the president. "Its Trump derangement syndrome." Republican Darrell Issa said he takes the FBI findings seriously but questions the timing coming days before the Trump-Putin meeting. "I personally would neither rule in nor rule out the validity."