Senate Judiciary Committee Chairman Lindsey Graham Lindsey Olin GrahamSenate Republicans signal openness to working with Biden Loeffler calls for hearing in wake of Netflix's 'Cuties' Quinnipiac poll shows Graham, Harrison tied in South Carolina Senate race MORE (R-S.C.) said on Tuesday that he has started closed-door interviews as part of his deep dive into the surveillance courts and the FBI’s Russia probe.

Graham confirmed to reporters that he has started the depositions, then escaped into a Senate elevator.

Graham is using his gavel to probe the Foreign Intelligence Surveillance Court (FISC) surveillance warrants involving Trump campaign associate Carter Page and the FBI’s handling of the investigation into Russia's election meddling and the Trump campaign.

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He’s requested testimony from more than 20 current Justice Department and FBI officials.

He also wants to call former officials including former FBI Director James Comey James Brien ComeyBarr criticizes DOJ in speech declaring all agency power 'is invested in the attorney general' Michael Cohen book debuts at top of bestseller list Trump offered Kelly FBI director's job, demanded loyalty: report MORE, former Deputy Attorney General Rod Rosenstein Rod RosensteinDOJ kept investigators from completing probe of Trump ties to Russia: report Five takeaways from final Senate Intel Russia report FBI officials hid copies of Russia probe documents fearing Trump interference: book MORE and former Deputy Attorney General Sally Yates Sally Caroline YatesButtigieg, former officials added to Biden's transition team The Hill's 12:30 Report: Delegates stage state-centric videos for the roll call Trump fires back at Yates for convention speech: 'Terrible AG' MORE before his committee.

The deep dive comes amid growing concerns about the potential for abuse of the FISC after Justice Department Inspector General Michael Horowitz found 17 “significant inaccuracies and omissions” in the Page warrant application.

Some of President Trump Donald John TrumpBarr criticizes DOJ in speech declaring all agency power 'is invested in the attorney general' Military leaders asked about using heat ray on protesters outside White House: report Powell warns failure to reach COVID-19 deal could 'scar and damage' economy MORE’s biggest allies want to use a debate over soon-to-expire provisions of the USA Freedom Act to make broader changes to the surveillance court.

Trump is convening a meeting on Tuesday afternoon with lawmakers on both sides of the debate to try to break the stalemate.

Congress has until March 15 to extend three provisions of the USA Freedom Act.