WASHINGTON – Just hours before Robert Mueller's report was finally released on Thursday, President Donald Trump unleashed a volley of tweets denouncing the probe as a historic "hoax" perpetrated by Democrats – taunting them in one post that employed a Game of Thrones theme.

Minutes after Attorney General William Barr read out a summary of the report to be released later in the day, Trump tweeted a picture of himself staring into the mists of battle with the tagline: "No collusion, no obstruction ... For the haters and the radical left Democrats ... Game Over."

Little more than an hour later, Trump repeated the "no collusion, no obstruction" line at a White House event honoring wounded warriors for their annual bike ride. "There never was," the president said, and he suggested he would look into how the investigation began.

"This should never happen to another president again – this hoax," Trump said.

Trump began the morning with a tweet that said "The Greatest Political Hoax of all time! Crimes were committed by Crooked, Dirty Cops and DNC/The Democrats."

Trump's critics said the barrage of tweets betrayed his anxiety about how the Mueller report will detail his actions with respect to Russia and the investigation.

"Hmm. I guess clicking your heels three times and saying 'total exoneration' doesn’t make it so," tweeted attorney Michael R. Bromwich, a former Justice Department official.

A series of more than ten tweets and re-tweets included a couple of short catchphrases Trump has used to describe the Mueller investigation: "PRESIDENTIAL HARASSMENT!" and "No Collusion - No Obstruction!" The latter tweet included videos of Trump repeatedly denying collusion with Russia, and complaining about the investigation.

The Mueller report itself provided more details of the investigation into Trump's presidential campaign and Russians who sought to influence the 2016 election, as well as claims that Trump may have tried to obstruct the investigation.

The Mueller report:Public to get first look at long-awaited results of inquiry into Russia, Trump campaign

6 things to look for:The Mueller report becomes public Thursday. Here are six things to look for.

Want news from USA TODAY on WhatsApp? Click this link on your mobile device to get started

The president has repeatedly denied wrongdoing and said the entire issue is political.

He has also tried to shift the blame to Democrats. On Thursday he re-tweeted Judicial Watch, the conservative educational foundation that has filed lawsuits seeking information from the FBI and the Barack Obama-era Justice Department about the conduct of the Russia investigation.

Attorney General William Barr issued a summary of the Mueller report on March 24, saying there was no evidence of coordination between the Trump campaign and Russians who sought to influence the 2016 election by stealing emails from prominent Democrats.

After the report:President Trump still facing swirl of investigations even after Robert Mueller's probe has ended

There will be 2 versions:Some members of Congress will see a less-redacted version of Mueller report, DOJ says

Barr also reported that Mueller did not reach a conclusion on the obstruction of justice question. The attorney general said his office determined there was not sufficient evidence to make a case against Trump.

Justice Department attorneys have spent recent weeks reviewing the report, redacting grand jury testimony and classified intelligence information before the report is made public.