In his report released Thursday, special counsel Robert Mueller found no evidence to support the allegations of collusion against Trump campaign adviser Carter Page that prompted the Obama administration's acquisition of surveillance warrants.

The report said the investigation "did not establish that Page coordinated with the Russian government in its efforts to interfere with the 2016 presidential election."

Republican lawmakers who now are determined to uncover the origins of the FBI's Trump-Russia counter-intelligence probe, which led to the Mueller investigation, are centering on the dubious "dossier" funded by Democrats that was used as evidence to obtain warrants to spy on Page.

The Justice Department and the FBI obtained a warrant from a FISA court in October 2016, just prior to the election. The warrant was renewed three times, with the final renewal coming in June 2017, a month after Mueller's investigation began.

Republican lawmakers, including the ranking member of the House Intelligence Committee, Devin Nunes, want to see the full documentation related to the FISA renewals. The June 2017 renewal was signed by Deputy Attorney General Rod Rosenstein and then-FBI Director Andrew McCabe.

The FBI was required to renew the warrant every 90 days by presenting evidence to the FISA court that Page was acting as an agent of the Russian government.

Investigative reporter Glenn Greenwald, known for his reporting of Edward Snowden's leak of documents revealing government spying, wrote Thursday via Twitter that he was surprised Mueller exonerated Page.

"The most amazing thing is that, as a Trump/Russia skeptic from the start, even I thought they would end up nabbing at least one American, like Carter Page, for conspiring with Russia. They didn't even get Carter Page! I *overestimated* what Mueller would find."

The then-Republican-led House Intelligence Committee found that the Justice Department and the FBI presented the anti-Trump dossier funded by Hillary Clinton campaign and the Democratic National Committee as primary evidence to obtain the warrants to spy on Page.

The author himself, former MI-5 spy Christopher Steele, has testified in court that the claims about Trump made in the dossier are "unverified."

Steele's dossier alleged Page worked with former Trump campaign manager Paul Manafort as a liaison with the Kremlin to engage in social-media operations and computer hacking. But Page and Manafort testified they didn't know each other, and Mueller found no evidence of the allegation.

Mueller also found no evidence to support Steele's charge that Page agreed to accept a bribe from Russia in exchange for the U.S. removing economic sanctions.

Now that the report is out

Republicans in the House and Senate who have been probing the origins of the Trump-Russia investigation are arguing that with the release of the Mueller report, the Justice Department no longer has the excuse of withholding relevant documents.

On Tuesday, the Republican chairmen of three Senate committees asked Barr to release "highly classified information" the FBI declined to examine as part of the Hillary Clinton email investigation.

A May 2016 FBI memo, the Republicans point out in a letter, states the information was "necessary" to complete the investigation into Clinton's handling of classified information on her private email server.

However, the FBI declined to review the material before closing the Clinton probe in 2016, Justice Department Inspector General Michael Horowitz found in a report released last year.