Former FBI Deputy Director Andrew McCabe needs to explain to Congress how he knew a field office possessed the anti-Trump dossier that became enmeshed in the Trump-Russia investigation, according to a top Republican senator.

Senate Judiciary Committee Chairman Lindsey Graham talked to Fox News's Sean Hannity on Monday about his review of the FBI's Crossfire Hurricane investigation and Foreign Intelligence Surveillance Act orders targeting onetime Trump campaign adviser Carter Page.

From McCabe, Graham said he wants to ask about July 2016, because when "they apply for a FISA warrant for Carter Page; it's turned down. McCabe says, 'Why don’t you go to New York? They've got a document that may help you.' It turned out to be the Steele dossier."

The South Carolina Republican said wants to know how McCabe knew British ex-spy Christopher Steele's dossier, which contained claims about President Trump's ties to Russia, was in New York, and "why didn’t they check it out before they used it" to obtain FISA warrants to wiretap Page.

The FBI's counterintelligence investigation into the Trump campaign's ties to Russia began in late July 2016. In spring 2019, special counsel Robert Mueller said he was unable to obtain enough evidence to charge any members of Trump's team with criminal conspiracy with the Kremlin.

Graham, a key Trump ally, offered more insight into what he hopes to glean in speaking with host Maria Bartiromo on her Fox News program Sunday Morning Futures.

"Who told McCabe that the document was in New York? And if McCabe thought it would help him with the warrant, why didn't he spend some time trying to find out if it was reliable? So that's what I'm looking at," the senator said. "Who knew what when? Did Rosenstein know that the dossier had been debunked by the time he signed the warrant? How could he not know?"

The Justice Department announced earlier this month that McCabe would not be charged in an investigation into whether he lied to investigators about a media leak two years ago, another matter with Republicans want to explore further. McCabe was fired in early 2018 and is now suing the Justice Department for wrongful termination, seeking to regain his job and back pay and claiming that Trump was behind the firing.

DOJ Inspector General Michael Horowitz released a report in December that concluded the FBI’s investigation was filled with serious missteps and concealed exculpatory information from the Foreign Intelligence Surveillance Court. Horowitz said at least 17 "significant errors and omissions" were discovered in the Page FISA applications spanning from fall 2016 to summer 2017. Page was suspected of being an agent for Russia but was never charged with wrongdoing.

The FISA filings relied upon a salacious and unverified dossier compiled by Steele, who had been hired by Fusion GPS, which in turn was hired by the Hillary Clinton campaign and the Democratic National Committee through the Perkins Coie law firm.

Graham recently told CBS News that he would seek private depositions and public testimony from four signers of the FISA warrants targeting Page to testify in the wake of the Justice Department watchdog’s report on FISA abuse: McCabe, former FBI Director James Comey, former Deputy Attorney General Sally Yates, and former Deputy Attorney General Rod Rosenstein.

The senator also plans to call current FBI Director Christopher Wray, who took over the bureau after Comey was fired in 2017 and wasn’t involved in approving FISA applications on Page, and asked Attorney General William Barr this month to make available 17 officials for transcribed interviews.

The FBI, Congress, and the FISA court itself have also been considering and implementing reforms following the inspector general's investigation.