In a stunning about-face, President Donald Trump said Tuesday that he had “full faith and support for America’s great intelligence agencies” — a day after he cast doubt on their conclusion that Russia meddled in the US elections while standing side-by-side with Vladimir Putin.

Speaking at the White House, he also said “I accept” the intel community’s verdict that meddling took place.

At one point during his remarks, the lights briefly dimmed.

“That must be the intelligence agencies,” Trump joked. “There it goes. OK. You guys OK? Good. That was strange.”

Trump also claimed that he misspoke during the joint news conference with Putin in Helsinki, and that he meant to say that he saw no reason why it would not be Russia that interfered in elections.

That was the opposite of his actual comment, which was: “[Putin] just said it’s not Russia. I will say this: I don’t see any reason why it would be.”

The president said he discovered the error by reviewing a transcript and watching a video clip of his remarks.

“I actually went out and reviewed a clip of an answer that I gave and I realize that there is need for some clarification. It should have been obvious. I thought it would be obvious but I would like to clarify just in case it wasn’t,” he said.

“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 I wouldn’t or why it wouldn’t be Russia.‘ So just to repeat it, I said the word would instead of wouldn’t. Sort of a double negative. So you can put that in, and I think that probably clarifies things pretty good.”

Trump also again insisted that Russia’s actions had no impact on the outcome of elections — and added that there “could be other people also [meddling]. There’s a lot of people out there.”

But the president did not respond when asked if he would publicly condemn the Russian strongman — and called his meeting with Putin a “tremendous success.”

And he repeated his claim that there was no collusion between his campaign and Russia, a question at the heart of special counsel Robert Mueller’s ongoing investigation.

“There was no collusion at all, and people have seen that and they’ve seen it strongly,” he said.

And he said the US would thwart any future efforts by Russia or anyone else to interfered in US elections.

“Unlike previous administrations, my administration will move aggressively to repeal any efforts and repel. We will stop it. We will repel it, any efforts to interfere in our elections.”

He charged that the Obama administration knew about Russian meddling but did nothing — even though the FBI’s investigation into Russian meddling began in the summer of 2016.

“They decided not to do anything about it. The reason they decided [was that] Hillary Clinton was going to win the election. They didn’t think it was a big deal. When I won the election they thought it was a big a sudden they went into action so it was given that in sharp contrast to the way it should be,” he said.

Moments before Trump spoke, Senate Majority Leader Mitch McConnell rebuked the president over his Helsinki comments.

“Over the last few years, the annexation of Crimea, the invasion of eastern Ukraine not to mention the indisputable evidence that they tried to impact the 2016 election” showed Russian hostility to the West, he said.

“So make no mistake about it, I would say to our friends in Europe, we understand the Russian threat and I think that is a widespread view here in the United States Senate among members of both parties.”

But House Republicans earlier used a party-line vote to block a Democratic measure aimed at condemning Trump’s stunning comments about Russia — the first vote testing how Congress would react to Trump’s remarks.

By 230-183, the House rejected a Democratic measure endorsing House Speaker Paul Ryan’s remarks criticizing Russia.

The Wisconsin Republican said “there is no question” that Russia interfered in the elections and that there is “no moral equivalence” between the two countries.