The Hill’s Editor-in-Chief Bob Cusack Robert (Bob) CusackThe Hill's Campaign Report: Biden asks if public can trust vaccine from Trump ahead of Election Day | Oklahoma health officials raised red flags before Trump rally Shakespeare Theatre Company goes virtual for 'Will on the Hill...or Won't They?' The Hill's 12:30 Report - Presented by Facebook - Big 10 votes to resume football season MORE said Friday that a potential Republican-led investigation into Hunter Biden’s business dealings in Ukraine is only a “matter of time.”

Cusack told Hill.TV that even though some congressional Republicans have indicated that they aren’t necessarily interested in going down that path, he argued that Trump’s allies like Majority Leader Mitch McConnell Addison (Mitch) Mitchell McConnellDemocratic senator to party: 'A little message discipline wouldn't kill us' House to vote on resolution affirming peaceful transition of power Republican lawyers brush off Trump's election comments MORE (R-Ky.) or Sen. Lindsey Graham Lindsey Olin GrahamLincoln Project mocks Lindsey Graham's fundraising lag with Sarah McLachlan-themed video The Hill's Morning Report - Sponsored by Facebook - Republicans lawmakers rebuke Trump on election Trump dumbfounds GOP with latest unforced error MORE (R-S.C.) could very well launch a separate committee investigation to look into the former Vice President’s son.

“He doesn’t want to have the spectacle,” Cusack said in reference to McConnell. “And when we talked to senators they’re like, ‘yeah I don’t think we want to mix impeachment with that’ as far as the trial.”

“But I think it’s a matter of time,” he added. “Senator Lindsey Graham is a little bit all over the place recently. He could launch it and he’s a Trump ally.”

Cusack’s comments come as President Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE appears to be facing some pushback from congressional Republicans over whether to call on Biden and his son Hunter to testify in the House impeachment inquiry.

Trump tweeted Thursday that the Bidens “must testify,” raising questions over whether the two would be brought in as part of the public impeachment trial.

“What did Hunter Biden do for the money?” @SenJohnKennedy A very good question. He and Sleepy Joe must testify!” Trump tweeted.

However, when asked about Trump floating that the Bidens should testify, Graham said he didn’t understand it as a "defense to the president,” adding “we’ll make that decision, not the president.”

Sen. John Cornyn John CornynHillicon Valley: Productivity, fatigue, cybersecurity emerge as top concerns amid pandemic | Facebook critics launch alternative oversight board | Google to temporarily bar election ads after polls close Lawmakers introduce legislation to boost cybersecurity of local governments, small businesses On The Trail: Making sense of this week's polling tsunami MORE (R-Texas), who has also repeatedly come to the president's defense on impeachment, told The Hill that he thought Republicans need to stay focused on the impeachment battle and "not go down any rabbit holes."

The GOP has sharpened its focus on Biden and his son as Trump's impeachment inquiry moves into the public phase. Open hearings are scheduled for next week as Democrats probe the president’s attempts to push foreign governments to investigate his political rivals.

—Tess Bonn