Sen. John McCain, meanwhile, issued a statement saying the "damage inflicted by President Trump's naivete, egotism, false equivalence, and sympathy for autocrats is hard to calculate".
"No prior president has ever abased himself more abjectly before a tyrant".
Taking direct issue with the president who appointed him, Director of National Intelligence Dan Coats said United States spy agencies have been "clear" and "fact-based" in their assessment that Moscow interfered in the presidential race two years ago - an assessment that Trump refused to endorse in Helsinki.
He added that the Kremlin doesn't have the means to surveil everyone that comes to the Russian Federation.
"President Trump proved not only unable, but unwilling to stand up to Putin", McCain said.
"And we get questions on the witch hunt and I don't think the people out in the country buy it, but the reporters like to give it a shot", he said.
At the press conference following the meeting, Trump declined to support the intelligence community's findings that Russian Federation had meddled in the 2016 presidential election on the basis of Putin's denial.
Mr Trump's eagerness to reach out to Mr Putin isn't unprecedented: since taking office in January 2017, he has shown admiration for a number of strongman leaders, from the Philippines' Rodrigo Duterte to North Korea's Kim Jong-un.
"I have great confidence in my intelligence people".
"The president of the United States today publicly sided with Russian Federation over our own Federal Bureau of Investigation on the subject of cyber attacks on our election campaign", Kimmel said after Trump met "his KGBFF" Putin.More news: No positive doping tests at Russian Federation 2018
"We shouldn't just let yesterday be swept under the rug, we have to explain American values and have to explain why they're in conflict with Putin's" Sasse said, suggesting that the USA should respond by ramping up further sanctions on the Russian government and Putin's "thugs".
In an exclusive interview, Fox News anchor Chris Wallace tried to do just that.
U.S. intelligence officers concluded, in 2016, that Russian Federation authorised cyber attacks and fake news stories on social media which aimed to increase the chances of Mr Trump getting elected.
"[Russia] remains hostile to our most basic values and ideals". Trump's USA opponents tried, in turn, to gain traction for the sarcastic hashtag lampooning his reluctance to criticise the Kremlin: #BAF (Blame America First).
Mr Trump added they had discussed disagreements between their countries "at length", and accepted that relations between them have never been worse.
"This is shameful", said Senator Jeff Flake, a fellow Republican and staunch critic of the president.
"Interference with the domestic affairs of the United States - 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?"
The language used by Democrats was much harsher, including accusations of "treason". He just said it's not Russian Federation.
Also on Monday, the U.S. government charged a Russian woman with conspiracy to act as an agent of the Russian Federation.
Wallace also voiced the question that was on the lips of all mainstream United States media on Monday: Was Trump so reluctant to criticize Putin because Russian Federation had some sort of dirt on him? As Donald Trump prepares to head home after three variously acrimonious, embarrassing and shocking visits to meet foreign counterparts, he will return to a country struggling to make sense of what he's spent his time overseas doing.