Sen. Ron Johnson announced his intent to subpoena Blue Star Strategies executives and produce records as part of an investigation into Burisma Holdings, a Ukrainian energy firm that once employed Hunter Biden.

The move by Johnson, the chairman of the Senate Homeland Security and Governmental Affairs Committee, marks a change in strategy one day after the panel scrapped a vote to subpoena a former consultant for the Washington-based consulting firm.

“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,” the Wisconsin Republican wrote in a letter Thursday to Michigan Sen. Gary Peters, the top Democrat on the committee.

The subpoena calls for every record between Jan. 1, 2013, to the present of work done by Blue Star Strategies on behalf of Burisma Holdings or individuals associated with Burisma, such as Burisma owner and Ukrainian oligarch Mykola Zlochevsky.

Burisma is the Ukrainian gas company on which Hunter Biden, son of the current Democratic presidential front-runner and former Vice President Joe Biden, served on the board from 2014 to 2019, including when the elder Biden took a leading role in carrying out U.S. policy toward Ukraine. President Trump and his allies have alleged the former vice president leveraged his position to protect his son from a Ukrainian investigation into Burisma's owner.

The subpoena also calls for Blue Star CEO Karen Tramontano and COO Sally Painter to testify before the committee about the documents the committee subpoenaed from their firm.

The subpoena of the Blue Star documents, Johnson noted in his letter to Peters, came after months of negotiations between Republicans and Democrats on the committee over issuing a subpoena to former Blue Star consultant Andrii Telizhenko. Democrats on the committee were reluctant to go forward with the Burisma investigation, urging Johnson to focus more on potential Russian interference in the 2020 election.

Telizhenko is a political official at the Ukrainian Embassy in Washington, D.C., who claimed former Democratic National Committee consultant Alexandra Chalupa wanted him to participate in anti-Trump operations during the 2016 presidential cycle. Chalupa has denied this accusation.

By Wednesday afternoon, Johnson said both Republican and Democratic members of the committee agreed to subpoena documents related to their investigation from Blue Star as opposed to Telizhenko himself.

“During the course of these discussions, the suggestion was made by both Democrat 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. I appreciate the engagement of our Committee members on this issue, and believe the appropriate course of action at this time is to accommodate that request,” Johnson wrote.

“Accordingly, pursuant to the Committee rules, this letter constitutes official notice that I intend to issue a subpoena to Blue Star, for the requests described in the enclosed schedule," Johnson said.

He added, “I stated I would seek documents from the consultant directly because, although he was willing to cooperate with the Committee's investigation, he was bound by a non-disclosure agreement,” Johnson said. “Conversely, Blue Star's responses to the Committee's December 3, 2019, request were incomplete.”

Tramontano recently told the New York Times her firm has provided dozens of documents to the Homeland Security panel and "will continue to cooperate" with the investigation "to the best of our ability.”