WASHINGTON — President Trump’s defiant mantra – “no collusion!” – became a rallying cry for his re-election Sunday after the Justice Department said there was no evidence that his campaign conspired with Russia during the 2016 election.

The four-page summary of special counsel Robert Mueller’s investigation removes one of the darkest clouds hovering over the Trump presidency, even though it reached no conclusion about whether he obstructed justice. Aides described Trump as gleeful, and the president cast it as a “complete and total exoneration” – despite Mueller’s more nuanced findings.

“There was no collusion with Russia, the most ridiculous thing I’ve ever heard,” Trump said underneath the wing of Air Force One as he prepared to return to Washington from a weekend at Mar-a-Lago.

The findings were an unmistakable political victory for Trump. They support his long-held stance about the Russia investigation, feed into his notion that the Washington establishment is out to get him and probably make it more difficult for House Democrats to investigate the president, who will similarly describe their efforts as illegitimate “witch hunts.”

The extent of his victory could be tempered, though, if Democrats succeed in their push for Mueller’s complete report to be released and the documents reveal questionable behavior by the president. Democrats made clear on Sunday that they wanted to see the full report and would call Attorney General William Barr to testify under oath.

Nonetheless, a feeling of euphoria swept over the White House staff Sunday as aides celebrated the end of the Mueller investigation, according to a senior White House official.

For nearly two years, the Mueller probe had been a source of great anxiety and stress in the halls of the West Wing. Some staffers hired lawyers to help them navigate the investigation, and many were fearful of becoming ensnared based on what they might overhear or witness. They described Mueller’s findings as a best-case scenario that would buttress the president’s mood, solidify Republican support and allow Trump to present a better message for re-election.

“What they do is they clear the deck for there to be an evaluation based upon his record as president,” said former New Jersey Gov. Chris Christie, a Republican and Trump ally, who called it a “very good day” for the president. “It lifts a cloud that was over the White House for the entire time he was there.”

Within an hour of learning the findings, Trump called for an investigation of his critics and cast himself as a victim. Aides say Trump plans to highlight the cost of the probe and call for organizations to fire members of the media and former government officials who he believes made false accusations about him, while aggressively mocking his critics and one of his favored enemies, the news media.

“Hopefully somebody is going to be looking at the other side,” Trump said, describing the Mueller investigation as “an illegal takedown that failed.”

“It’s a shame that our country had to go through this,” Trump said. “To be honest, it’s a shame that your president has had to go through this.”

White House aides and Trump allies moved quickly to take advantage of the moment. Campaign officials released a lengthy video called “Collusion Hoax!” and White House officials issued a flurry of talking points that defended the president while attacking Democrats.

Republican National Committee officials issued a long set of “talking points” that delineated the cost of the probe – $50,230 per day for 675 days, in their calculation – and attacked the news media and Democrats for extensively focusing on the investigation.

Aides and Trump allies said they believe the findings will bolster the credibility of the president – who traffics in untruths and conspiracy theories – while also undermining Democrats, some of whom have predicted that Trump would be found guilty of conspiring with the Russians and obstructing Mueller’s investigation.

One former White House official said the Democrats have “just handed the Trump campaign the greatest election issue in modern political history, on a silver platter.”

Douglas Brinkley, a presidential historian at Rice University, said: “Trump actually kind of has inoculation now against other charges against him because he was able to prove his innocence here. It allows Donald Trump to build his narrative about how the news media and the Democrats created this whole Russia collusion hoax, in Trump’s mind.”

The Mueller probe led to guilty pleas or charges against a number of the president’s top aides, including his former campaign manager and national security adviser. A number of Trump officials also pleaded guilty or were charged for lying about their interactions with Russians, and dozens of Russians were indicted, though they are unlikely to appear in court.

On the matter of obstruction, Mueller stopped short of clearing Trump, saying that “while this report does not conclude that the president committed a crime, it does not exonerate him.”

A variety of other criminal investigations still hover over the president: His company, his inaugural committee and some of his allies remain under scrutiny by state and federal investigators, including in the Southern District of New York.

“There is always peril there,” Christie said. “I’ve always thought that the SDNY investigation was much more dangerous than the Mueller investigation because it has no restriction on its scope.”

In Washington, Democrats plan to make “abuse of power” a focus of their investigations going forward, several Democratic aides said, looking for instances in which the president or his administration hurt working-class Americans or in which the president behaved outside the norms of the presidency.

Democrats are likely to bring Trump aides to Capitol Hill to describe situations that could be embarrassing for him. And other oversight probes on the Hill, including abuses of security clearances, could cause pain for Trump.

“The ongoing investigations that have just started with a Democratically controlled House will reach a fever pitch now that the special prosecutor has not been able to deliver the political goods as they wanted,” said Rep. Mark Meadows, R-N.C., a Trump ally. “I see the level of investigations being ramped up with an exponential fervor that we have not seen in the first 90 days of Nancy Pelosi’s speakership.”

Trump was buoyant all weekend because the investigation was over, golfing with Kid Rock and Sen. Lindsey Graham, R-S.C., greeting donors and supporters at a political dinner and hanging out with friends on the Mar-a-Lago patio.

He was briefed on the findings by his legal team just before he left his Florida resort, and he immediately told aides that he wanted to speak. All weekend, he remained silent as even his top officials did not know what Barr would include in the report, written without consultation from Mueller.

“This is very good,” Trump responded after hearing from his lawyers, according to White House spokesman Hogan Gidley. Gidley said Trump talked to staffers, watched TV and made calls during the flight and had not seen the full report. “He’s just very happy with how it all turned out,” Gidley said aboard the plane.

Those who know Trump best say he was most furious that the probe detracted from his political instincts and felt under siege from critics who would never accept him as a legitimate president. “It’s never going to end,” he would say, according to a former senior administration official.

Trump took particular pride that he never sat for an interview – essentially winning a showdown with the special counsel’s office, which received only one round of written answers from the president, advisers said.

“I think how Trump is going to portray this is that the establishment took a shot at him and missed,” said John Feehery, a former Republican leadership aide. “The Democrats are going to have a hard time not looking really partisan now, and that’s to their detriment.”

An ebullient Trump went into the cockpit of Air Force One for the landing Sunday night to celebrate with his pilot, who was retiring after the flight, a White House official said.

When he came back to the White House, he declined to take questions but briefly stopped on the South Lawn. “I just want to tell you, America is the greatest place on Earth. The greatest place on Earth.”