Republicans hope to learn more about U.S. Attorney John Durham's review of the Russia investigation when Attorney General William Barr testifies next month.

Rep. Doug Collins, the ranking member of the House Judiciary Committee, offered some insight on Sunday into what questions he and his GOP colleagues might ask about the secretive investigation.

"I want to hear more about the Durham investigation," the Georgia Republican said on Fox News's Sunday Morning Futures with host Maria Bartiromo. "Is there still adequate resources, everything needed there?"

Barr was called to testify by House Democrats, who seek answers about the Justice Department's conduct, including the scaled-back sentencing recommendation for longtime Trump associate Roger Stone and matters related to Russia and Ukraine.

Republicans have their own priorities. According to Collins, the GOP side will focus on why the Justice Department dropped its criminal investigation into former FBI Deputy Director Andrew McCabe and Foreign Intelligence Surveillance Act reform following a scathing DOJ watchdog report.

The hearing is scheduled for March 31.

Durham, the top prosecutor in Connecticut, was assigned to the review of the Russia investigation by Barr, who said last spring "some of the facts" surrounding the inquiry "don't hang together with the official explanations of what happened." Democrats have criticized the review as a politically motivated scheme to undermine the work of former special counsel Robert Mueller and attack President Trump's perceived enemies.

In October, Fox News reported that Durham expanded the investigation, broadening his team to include additional agents and resources as the period of time they were examining expanded into 2017. Weeks later, it was revealed that Durham opened a criminal inquiry in his investigation, which gave the federal prosecutor the power to impanel a grand jury and hand down indictments. Former FBI lawyer Kevin Clinesmith, who altered a key document in FISA filings related to onetime Trump campaign adviser Carter Page, is the only person publicly known to be under criminal investigation by Durham.

Texas Rep. John Ratcliffe, a Republican member of the House's judiciary and intelligence panels, told Bartiromo on Sunday he believes Durham is "specifically" looking into alleged FISA abuses, noting the Justice Department already determined that at least two of the four FISA orders targeting Page were not valid.

Another guest on Sunday Morning Futures, Senate Judiciary Committee Chairman Lindsey Graham, talked about his "deep dive" inquiry into the origins of the Russia investigation and FISA issues, saying he is eager to question former Deputy Attorney General Rod Rosenstein, who appointed Mueller in May 2017 shortly after Trump fired former FBI Director James Comey.

In December, Barr said Durham's inquiry into the Russia investigation could wrap up by the spring or summer of 2020.