“I never thought I would see the day when our American president would stand on the stage with the Russian president.”

WASHINGTON — Donald Trump returned late Monday from his European tour to face ire in Washington, where US 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.

Republican Sen. John McCain said Trump’s seeming acceptance of Putin’s denial was a historical “low point” for the US presidency and the Helsinki summit between the two leaders a “tragic mistake.”

“Today’s press conference in Helsinki was one of the most disgraceful performances by an American president in memory. The damage inflicted by President Trump’s naivete, egotism, false equivalence and sympathy for autocrats is difficult to calculate,” McCain said in a blistering statement.

“No prior President has ever abased himself more abjectly before a tyrant,” he added.

Senior Republican Sen. Lindsey Graham said Trump’s answer on meddling “will be seen by Russia as a sign of weakness.”

Bent on forging a personal bond with the Kremlin chief, Trump headed into the summit blaming the “stupidity” of his predecessors for plunging ties to their present low.

“This is shameful,” said Sen. 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.”

Taking direct issue with the president who appointed him, Director of National Intelligence Dan Coats said US 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.

It was an extraordinary press conference closing out the Trump-Putin summit, in which the American president delivered what amounted to a warm embrace to the man who for years has been isolated by the US and Western allies for Russia’s activities in Ukraine, Syria and beyond.

Trump said he and Putin “spent a great deal of time” discussing allegations of Russian election meddling as they met for several hours Monday. But Trump declined the opportunity to denounce Putin for the interference efforts, which US intelligence agencies insist did occur, including hacking of Democratic emails, the subject of last week’s indictment of 12 Russians.

Trump said, as he has countless times, that there was “no collusion” between his campaign and the Russians. “We ran a brilliant campaign and that’s why I’m president,” he said.

Putin also suggested Monday that Moscow and Washington could jointly conduct criminal investigations into a dozen Russian intelligence officials accused of hacking during the 2016 US election campaign — an idea Trump hailed as an “incredible offer.”

Asked if Russia could extradite the 12 Russian military intelligence officers, Putin challenged the US to take advantage of a 1999 agreement envisaging mutual legal assistance.

He said the agreement would allow US officials to request that Russian authorities interrogate the 12, adding that US officials could request to be present in such interrogations.