US President Donald Trump claims he misspoke during his joint press conference with Vladimir Putin when he publicly challenged the US intelligence conclusion that Russia meddled in the 2016 election.
At his inaugural summit with the Russian president in Finland, Trump appeared to accept at face value the strongman's denial that Moscow interfered in a bid to undermine the Democrat Hillary Clinton - a stance that triggered bipartisan outrage at home.
Trump said of Putin in Helsinki: "He just said it's not Russia. I will say this: I don't see any reason why it would be."
But faced with outrage at home, with even some of his political allies demanding that he reverse course, Trump - in an extraordinary postscript to the summit - sought to walk back his remarks.
"In a key sentence in my remarks, I said the word 'would' instead of 'wouldn't'. The sentence should have been: 'I don't see any reason why it wouldn't be Russia'."
US President Donald Trump and Russian President Vladimir Putin in Helsinki, Finland Source: AP
"Sort of a double negative," he added - repeating the laborious clarification several times.
But while the US leader expressed his "full faith and support for America's great intelligence agencies," he insisted that "Russia's actions had no impact at all on the outcome of the election."
Earlier in the day, Trump sounded a defensive note, insisting his meeting with Putin had been "even better" than his one last week with traditional allies NATO - a testy gathering seen as having badly strained trans-Atlantic ties.
The US president has found precious little support for his decision not to confront Putin and faced calls even from allies to change tack.
"He has to reverse course immediately and he's gotta get out there as soon as possible before the concrete starts to set on this," former White House communications director Anthony Scaramucci said on CNN.
"Loyalty right now requires you to tell the truth and sit with him and explain to him the optics of the situation, why the optics are bad, the strategy in terms of trying to get along with Vladimir Putin and deploying a strategy of going against the intelligence agency is very bad," Scaramucci said.
Former House speaker and longtime Trump ally Newt Gingrich put it yet more bluntly.
"President Trump must clarify his statements in Helsinki on our intelligence system and Putin," he tweeted as Trump headed home. "It is the most serious mistake of his presidency and must be corrected - immediately.
Trump's performance at the summit has even come under fire from the hosts at Fox News, usually a reliable defender of the president.
"No negotiation is worth throwing your own people and country under the bus," Fox anchor and Fox & Friends co-host Abby Huntsman - the daughter of the US ambassador to Russia - wrote on Twitter.
And former president Barack Obama, who has remained above the political fray since leaving office, appeared to allude to the events of the day before during a rare public appearance Tuesday at which he warned the world had plunged into "strange and uncertain times."
"Strongman politics are ascendant, suddenly, whereby elections and some pretence of democracy are maintained - the form of it - but those in power seek to undermine every institution or norm that gives democracy meaning," Obama said in Johannesburg.
'Undermine democracy'
Special Counsel Robert Mueller's investigation into Russian meddling and possible collusion with the Trump campaign has increasingly put pressure on the White House, and the president - who regards it as an attack on his legitimacy - has dubbed it a "witch hunt."
But the investigation continues to progress, resulting in the indictment of 12 Russian military intelligence agents on Friday - timing that was embarrassing in light of the upcoming summit.
While Trump has faced intense criticism over Helsinki, he is not entirely without defenders.
Republican Senator Rand Paul has given a series of interviews supporting Trump's stance towards Putin and berating his critics as biased.
"I think the president did a good thing by meeting with Putin and I think it's a mistake for people to try to turn this into a partisan escapade," the Kentucky Republican said on CBS.
Paul's efforts drew praise from Trump, who tweeted: "Thank you @RandPaul, you really get it!"
US House Speaker Paul Ryan has criticised Donald Trump for his remarks in Helsinki. Source: AP
But the bipartisan consensus has been broadly hostile to Trump's stance - as the top Republican in Congress, House Speaker Paul Ryan made clear once more at a press conference Tuesday on Capitol Hill.
"We stand by our NATO allies and all those countries who are facing Russian aggression," Ryan said. "Vladimir Putin does not share our interests, Vladimir Putin does not share our values."
"We just conducted a yearlong investigation into Russia's interference in our elections. They did interfere in our elections. It's really clear. There should be no doubt about that," he said.
"Russia is trying to undermine democracy itself."
