"Missed opportunity by President Trump to firmly hold Russian Federation accountable for 2016 meddling and deliver a strong warning regarding future elections", Republican Senator Lindsey Graham said on Twitter.
Donald Trump returned late on Monday from his European tour to face ire in Washington, where U.S. intelligence officials and senior Republicans were denouncing the president as "shameful" and "disgraceful" after he refused to challenge Russian leader Vladimir Putin over interference in American elections. One was House Speaker Paul Ryan who said in a statement that "there is no question that Russian Federation interfered" in the election. His performance was denounced as "treasonous" by a former Central Intelligence Agency chief, while senator John McCain said the summit was "a tragic mistake".
Mr Putin denied the interference claim.
Putin pointed out that Mueller's previous indictment, against 13 Russians and a catering company, was being contested in a United States court, which "has not discovered any trace of interference whatsoever".
Even for Trump's high-drama, tweet-driven presidency, this was the most heavily criticised trip overseas of his 18 months in office.
"Do you really believe that someone acting from the Russian territory could have influenced the United States and influenced the choice of millions of Americans?"
"Anyone who just believes President Putin given his record is someone who you could probably sell the Brooklyn Bridge to", Provizer said.
Rep. Will Hurd, R-Texas, said he's seen Russian intelligence manipulate many people in his earlier career as a CIA officer. We need to continue to deal with Russian Federation from a position of strength.
Others with less direct roles weighed in as well, to reaffirm their belief that Russian Federation in fact was the agent that meddled in the campaign.
What has United States reaction been?
It was disgraceful. It was a betrayal, not only of our intelligence agencies but of everyone who has fought against the threat that Russian Federation poses to the United States and its allies.
Instead, he denounced the "stupidity" of his own country's policy, especially the decision to investigate election interference.
Bob Corker, the Senator for Tennessee, told broadcaster CNN: "The President's comments made us look as a nation more like a pushover and I was disappointed in that". That's not to say it will fundamentally change the course of his presidency, given the fluidity of events, the reality that attention spans are short and the probability of more shocks from various directions that will put the focus elsewhere.
We agree with Republican Sen. Later, the House Democratic Leader Nancy Pelosi agreed with Schumer and said the press conference "proves the Russians have something on the president, personally, financially or politically".
We saw our president once again malign the Federal Bureau of Investigation and Justice Department for investigating Russian interference in our 2016 election, then decline to object when Putin denied his country's involvement.
Trump's statements at Monday's news conference prompted some Democrats to publicly speculate about the reasons behind his deference to Putin.
Looking back over the week, from Brussels to Britain to Helsinki, Trump's message has been clear, consistent and startling.
Trump stunned U.S. political allies and foes alike with his answer to a question about Russian hacking and interference in the 2016 election, which saw him defeat Democrat Hillary Clinton. "That's the "thanks for keeping the the tape between us guys" wink", he said.
"Well, first of all, all of us have plenty of political rivals".
European allies are uneasy.
Ryan, the top Republican in the US House of Representatives, was tempered in his remarks but insisted that Trump "must appreciate that Russian Federation is not our ally".
One US senator suggested Trump check it for listening devices and never let it enter the White House. "This is utterly ridiculous".
What steps of that nature might have come out of today's meeting, and what do you expect for U.S. -Russia relations going forward?