Attorney General William Barr on Sunday released the "principal conclusions" of Special Counsel Robert Mueller's completed Russia probe in a bombshell four-page letter to Capitol Hill lawmakers, which stated definitively that Mueller did not establish evidence that President Trump's team or any associates of the Trump campaign had conspired with Russia to sway the 2016 election -- "despite multiple offers from Russian-affiliated individuals to assist the Trump campaign."

For Trump, who has tweeted more than 230 times that he did not collude with Russians amid a torrent of allegations from media and political figures, the moment amounted to a near-total vindication. Although Mueller noted that his report did not "exonerate" Trump on obstruction, Barr wrote, the "report does not recommend any further indictments, nor did the Special Counsel obtain any sealed indictments that have yet to be made public."

"No Collusion, No Obstruction, Complete and Total EXONERATION," Trump wrote on Twitter Sunday afternoon. "KEEP AMERICA GREAT!"

Later, he told reporters, "It was just announced there was no collusion with Russia, the most ridiculous thing I've ever heard. There was no collusion with Russia, there was no obstruction. ... It's a shame that our country had to go through this, to be honest, it's a shame that your president has had to go through this -- since before I even got elected, it began. And it began illegally. Hopefully someone is going to look at the other side. This was an illegal takedown that failed."

Mueller's team specifically looked into two Russian efforts to interfere with the 2016 election -- first, the work by a Russian organization, the Internet Research Agency (IRA), to "conduct disinformation and social media operations" designed to "sow discord" in the United States.

According to Barr's letter, "the Special Counsel did not find that any U.S. person or Trump campaign official or associate conspired or knowingly coordinated with the IRA in its efforts, although the Special Counsel brought criminal charges against a number of Russian nationals and entities in connection with these activities."

Next, Mueller investigated whether the Trump team was involved in the hacking of emails, many of which were released publicly through intermediaries like WikiLeaks, that belonged to the Hillary Clinton campaign and the Democratic National Committee (DNC).

READ THE FULL LETTER

"The Special Counsel did not find that the Trump campaign, or anyone associated with it, conspired or coordinated" with Russians who worked on those hacking efforts, according to Barr's letter, "despite multiple offers from Russian-affiliated individuals to assist the Trump campaign."

Mueller's report did not reach a conclusion on whether the Trump campaign obstructed justice, and left that decision to Barr and officials at the DOJ -- who determined there was insufficient evidence of obstruction. Mueller "recognized," according to Barr's letter, that the lack of evidence that Trump was involved in collusion would undercut any obstruction case -- which would depend on showing a corrupt intent by the president.

"The Special Counsel therefore did not draw a conclusion - one way or the other - as to whether the examined conduct constituted obstruction," according to Barr's letter. "Instead, for each of the relevant actions investigated, the report sets out evidence on both sides of the question and leaves unresolved what the Special Counsel views as 'difficult issues' of law and fact concerning whether the President's actions and intent could be viewed as obstruction. The Special Counsel states that 'while this report does not conclude that the President committed a crime, it also does not exonerate him.'"

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Barr's letter concluded: "After reviewing the Special Counsel’s final report on these issues… Deputy Attorney General Rod Rosenstein and I have concluded that the evidence developed during the Special Counsel’s investigation is not sufficient to establish that the President committed an obstruction-of-justice offense."

"This was an illegal takedown that failed." — President Trump

"Our determination was made without regard to, and is not based on, the constitutional considerations that surround the indictment and criminal prosecution of a sitting president," Barr stated.

Barr said Mueller's team "thoroughly" investigated allegations that Trump's team sought to conspire with Russians or obstruct investigators. The Special Counsel "issued more than 2,800 subpoenas, executed nearly 500 search warrants, obtained more than 230 orders for communication records, issued almost 50 orders authorizing use of pen registers, made 13 requests to foreign governments for evidence, and interviewed approximately 500 witnesses," Barr wrote.

Barr's disclosure was a capstone moment following the 22-month investigation that ensnared six former Trump advisers and associates -- but resulted in no indictments related to collusion with Russia.

The letter promised to settle some of the largest outstanding questions of the Mueller investigation, even as Democrats on Sunday vowed to press on with other investigations, and members of both parties continued to push for the public release of as much of the Mueller report as possible.

Barr's letter noted that he would work quickly with Mueller to determine which sections of the report could be released, and which needed to be withheld because they contained sensitive grand jury-related matters shielded by law. A DOJ official confirmed to Fox News that the process of determining what information can be released has already begun.

Trump's personal legal team, including Rudy Giuliani, Jay Sekulow, Jane Serene Raskin, and Martin R. Raskin, declared victory late Sunday.

“As we have stated from the very beginning, there was no collusion and no obstruction," the lawyers said. "This is a complete and total vindication of the President.”

In response to Barr's letter, House Judiciary Committee Chairman Jerry Nadler, D-N.Y., tweeted: "Seems like the Department of Justice is putting matters squarely in Congress’ court."

Nadler, speaking to "Fox News Sunday," insisted, "So we know a lot of things and maybe it’s not indictable, but we know there was collusion. The question is the degree."

Along those lines, Nadler said that Democrats would continue their efforts.

"The job of Congress is much broader than the job of the special counsel," Nadler said. "The special counsel is looking and can only look for crimes. We have to protect the rule of law, we have to look for abuses of power, we have to look for obstructions of justice, we have to look for corruption in the exercise of power which may not be crimes."

But House Judiciary Committee Ranking Member Doug Collins, R-Ga., speaking to "Fox News Sunday," argued that Democrats were unlikely to uncover anything Mueller could not.

"As we’ve seen in the first two months of this Congress, [Democrats] really don’t have a policy agenda," Collins said. "They have an agenda against the President. They have an agenda to try and win 2020. And so, what we’re seeing is, they think that they can go into the Judiciary Committee or any other committee and have a limited budget, limited subpoena power, limited staff and go up against an investigation that lasted 22 months, had unlimited power, unlimited subpoena power, had plenty of investigators -- and they think they can find something more than what they did, then I think they’re sadly mistaken."

A former senior law enforcement official echoed those remarks, telling Fox News that Democrats would lack key investigative powers that Mueller had, including the ability to convene grand juries -- and that Nadler's path amounted to trying to criminalize meetings with foreign actors that the special counsel apparently determined were simply not criminal.

“With all the talk of the Democrats intensifying their House investigations," the former official said, it was important to note that "unlike Special Counsel Mueller, Congress and the [DOJ Inspector General] cannot convene grand juries and initiate prosecutions. If Mueller couldn't find collusion or conspiracy with every investigative tool, what do the Democrats expect to accomplish?"

Top Democrats in Congress had scrambled to respond to the end of the Mueller probe this weekend, holding an emergency conference call and discussing potential next steps.

A top Democrat on the Senate Judiciary Committee conceded to reporters Saturday that Barr's release of Mueller's conclusions likely would be a cause for celebration among President Trump's supporters -- many of whom have stood by the president for more than two years amid a torrent of unproven allegations that the Trump campaign illegally worked with Russia to influence the 2016 election.

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"It's the end of the beginning but it's not the beginning of the end," Delaware Sen. Chris Coons said, echoing his party's strategy of moving forward on to other investigations, including probes into Trump's financial dealings. "Once we get the principal conclusions of the report," he added later, "I think it's entirely possible that that will be a good day for the president and his core supporters."

Some conservatives, meanwhile, argued that Democrats should come under increased scrutiny for their contacts with foreign nationals. Hillary Clinton's campaign and the Democratic National Committee (DNC) hired the firm Fusion GPS, which employed Britsh ex-spy Christopher Steele to produce an anti-Trump dossier that the FBI used to justify the surveillance a top Trump aide and kickstart the Russia probe -- even as text messages exclusively obtained by Fox News this week revealed that the DOJ seemingly raised "repeated" concerns that Steele, whose anti-Trump views are now widely known, was politically biased.

The Trump aide, Carter Page, has not been charged with any wrongdoing, although the FBI initially alleged he had conspired with Russians.

On Sunday, Ohio GOP Rep. Jim Jordan said Sunday that if the Mueller report is disclosed publicly, then all documents relating to it should also be published -- including the complete Foreign Intelligence Surveillance Act (FISA) warrant application to monitor Page.

"We have asked for that information to be made public a long time ago,” Jordan said in a televised interview.

In a show of confidence, for his part, Trump waved and flashed two thumbs up to supporters as he returned to his Mar-a-Lago estate in Florida on Saturday. The entertainer Kid Rock later uploaded a photograph of his golf outing with Trump earlier in the day.

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On Sunday morning, Trump broke an unusual, nearly 40-hour-long Twitter silence, writing simply, "Good Morning, Have A Great Day!"

He added, minutes later: "MAKE AMERICA GREAT AGAIN!"

Fox News' Jake Gibson at the Justice Department and Chris Wallace contributed to this report.