A leading Senate Republican said on Monday he would ask Attorney General William Barr to appoint a special counsel to probe whether U.S. law enforcement officials made missteps in their investigation into possible collusion between President Donald Trump's campaign and Russia.

A day after the attorney general said the report by special counsel Robert Mueller found Trump's campaign did not conspire with Russia, Senate Judiciary Committee Chairman Lindsey Graham said: "We will begin to unpack the other side of the story."

He said it was time to look at the origins of a Foreign Intelligence Surveillance Act (FISA) warrant for former Trump adviser Carter Page, which was based in part on information in a dossier compiled by Christopher Steele, a former British intelligence officer who co-founded a private intelligence firm.