Wisconsin Republican Sen. Ron Johnson who serves as the chairman of the Senate Homeland Security Committee said Thursday he plans to continue with a subpoena on a consulting firm tied to Hunter Biden and Burisma, a Ukrainian gas company.

Johnson had originally planned to subpoena Andrii Telizhenko, a consultant for the firm Blue Star Strategies contracted to do work with Burisma, but cancelled the committee vote scheduled for Wednesday after “discrepancies” in FBI briefings on Capitol Hill.

“There were discrepancies in what had been told in one briefing versus the next briefing, and then even greater discrepancies in staff notes,” Johnson wrote to members of the committee, according to The Hill.

Now Johnson is aiming to compel Blue Star Strategies to turn over records related to Burisma and bring forward the firm’s co-founders, Karen Tramontano and Sally Painter.

“This subpoena is in furtherance of the committee’s ongoing work to address the many unanswered questions about potential conflicts of interest and the extent to which representatives of Burisma – including officials at Blue Star – used individuals with close personal connections to high-level officials within the Obama administration to gain access to and potentially influence U.S. government agencies,” Johnson wrote in a letter to ranking Democratic Sen. Gary Peters of Michigan.

Johnson is seeking the consulting firm’s records related to Burisma going back to Jan. 1, 2013 to present. Biden joined Burisma’s board in April 2014, and according to the Daily Caller, connected Blue Star with the Ukrainian energy company in 2015 to combat corruption charges.

“The suggestion was made by both Democratic and Republican members of our committee that we should issue a subpoena directly to the source of the documents relevant to our work: Blue Star,” Johnson wrote to Peters.

The request for subpoenas came as part of a broad investigation into Biden’s perceived conflicts of interest conducting overseas business launched in 2017 by Johnson and Sen. Chuck Grassley of Iowa who serves as chairman of the Senate Finance Committee.

While his father, former Vice President Joe Biden, was dictating U.S. policy towards Ukraine in the Obama White House, Hunter Biden was hired on the board of Burisma earning upwards of $50,000 a month despite no prior experience in the industry. A Federalist analysis of Hunter Biden’s pay reveals he was being showered in excess compensation when compared to the level of pay given to board members of even larger corporations. Hunter Biden also flew aboard Air Force Two on a trip with his father to China that was followed by a series of transactions that benefited Biden’s firm.

The Senate probe began to garner widespread media attention last fall after a transcript was released of President Donald Trump’s phone call with Ukraine President Volodymyr Zelensky, in which Trump mentioned Biden’s work in Ukraine that ultimately led to impeachment. On the day of Trump’s acquittal in the Senate, Grassley and Johnson issued demands for Secret Service travel records on Biden to determine whether Biden “used government-sponsored travel to help conduct private business” with nations abroad.

The two top Republican senators have also asked for records on Biden from a wide range of government agencies who appear to be cooperating with the senators’ requests. Last month, Democratic Sen. Ron Wyden leaked to the press that the Treasury Department had been supplying the senators with documents showing “‘evidence’ of questionable origin,” in the form of Suspicious Activity Reports (SARs) related to Biden’s overseas work.

Grassley and Johnson responded by pointing out it was “strange that any senator would complain about Congress receiving responses to oversight requests in a timely manner.”