President Donald Trump's strategist warned him not to fire FBI director James Comey. His advisors told him to stop tweeting about the Russia investigation. And his lawyers encouraged him to cooperate.

Trump ignored them all, and could still claim vindication Thursday after the Mueller report cleared him of collusion charges.

He beat back the investigation that threatened his presidency with constant attacks on investigators and the media, a canny narrative that denied obvious facts, nonstop trolling of opponents on Twitter, and a crafty legal stall.

It was hugely risky, but it appears to have paid off - notwithstanding further investigations Congressional Democrats have promised into Trump's alleged abuse of his authority.

Special Counsel Robert Mueller's report Thursday ruled that Trump's campaign did not criminally conspire with Russians to skew the 2016 election, and drew no conclusion on allegations of obstruction.

That allowed Trump's hand-picked Attorney General Bill Barr to declare the president fully cleared.

"As I have been saying all along, NO COLLUSION - NO OBSTRUCTION!" Trump tweeted in a fist-pump of victory.

'Witch hunt'

Trump began his campaign well before Mueller arrived, denying during 2016 that Russia was interfering in the election, even though US spy chiefs said they were.

He could have just accepted it, but the claim marred his election victory. So he called it "fake news" and said the intelligence community was out to undermine him.

He made things worse in May 2017 when, angered by the ongoing probe into Russian meddling, he fired Comey.

The result was Mueller's appointment to lead the Russia investigation, expanding it to include obstruction of justice.

"This is the end of my presidency. I'm fucked," Trump said that day, according to Mueller's report.

But the next day, he switched gears into offense, launching a grinding public relations war guided mostly by his own instincts.

"This is the single greatest witch hunt of a politician in American history!" he tweeted.

It was pure Trump style - weaving a narrative that struck a chord with his supporters and riled his opponents.

The Russia allegations were a hoax, he alleged, Democrats were trying to avenge Hillary Clinton's election defeat, and Comey and Mueller were corrupt.

With Fox News, influential with the political right, echoing his claims, voters who formed Trump's electoral base bought the story of a "witch hunt."

Legal team turmoil

Trump often proved his own enemy. His staff struggled to block his orders to remove Mueller, which could have resulted in impeachment. 

His constant attacks on Mueller's investigators, the Justice Department, and potential witnesses against him bolstered the allegations of obstruction.

And his legal team was in constant turmoil, wrestling with a client who didn't follow advice or tell them the truth. 

Early members of the team wanted to cooperate with Mueller, seeing that as the president's best option.

But for Trump, it was not about law, but image, and the best approach was guerilla warfare fought through the media and Twitter.

With Mueller's investigators closing in on the White House in early 2018, Trump churned his team, recruiting attorneys who would fight back. 

He hired Rudy Giuliani, a fellow New Yorker who like Trump saw the challenge as a street fight.

Giuliani fed reporters tidbits behind the scenes and went on television with tactical denials and counterattacks that may have had little real substance but supported Trump's claim that he was under political assault.

By mid-2018 Trump appeared to have scored a major victory: seeing his ability to hold onto his conservative base, Republicans rallied behind him ahead of the November elections.

'Perjury trap'

Crucial to Trump's success, too, was avoiding being interviewed by the investigators.

"I'm looking forward to it, actually," he declared in January 2018.

Behind the scenes his team stalled, first demanding written questions, then arguing over which questions they would answer.

Giuliani accused Mueller of setting up a "perjury trap," saying his client, known for liberally delivering falsehoods and sometimes spilling truths he should withhold, was being set up.

Meanwhile, the White House pressured Mueller to wrap up the investigation, saying he was spending too much money on the ever-spiraling probe.

Finally Mueller's team agreed to take written answers, which arrived only in late November. 

The answers were "inadequate," the Mueller report said: Trump replied more than 30 times that he could not recall something, and elsewhere gave incomplete or imprecise responses.

But when Mueller's team sought to follow-up in person, Trump refused.

By that time, Mueller's team realised it was too late in the investigation to launch into a constitutional fight with the White House. They opted to go with what they had.

The Barr factor

Trump's final coup was to replace attorney general Jeff Sessions with Bill Barr.

Trump wasn't acquainted with the Washington corporate lawyer, but he learned that Barr was a critic of Mueller who had a constitutional argument against Trump being charged with obstruction.

Trump's dismissal of Jeff Sessions in November opened the door for Barr to become attorney general, someone who would be able to find a legal way to protect Trump from charges.

Barr did the job: after seeing Mueller's conclusions, he declared that the evidence on obstruction did not amount to enough to charge the president, and that was that.

Trump had won.