House Republicans are moving closer to opening an impeachment inquiry after the transcribed interviews and public testimony earlier this summer by two IRS whistleblowers regarding the government’s handling of its investigation into President Joe Biden’s son, Hunter Biden. 

The whistleblower testimony about the probe was a “game changer” according to a senior GOP aide, who told CBS News that with what House Republicans believe is significant new evidence uncovered by their committee investigators, the “momentum is going toward opening an impeachment inquiry.” 

The aide said September would be a pivotal month, with the anticipated testimony of Attorney General Merrick Garland before the House Judiciary Committee. Garland is expected to be pressed by Republicans about apparent discrepancies in statements about the authority held by then-U.S. Attorney David Weiss to bring charges in the five-year investigation of Hunter Biden.  

White House spokesperson Ian Sams said, “This baseless impeachment exercise would be a disaster for congressional Republicans, and don’t take our word for it: just listen to the chorus of their fellow Republicans who admit there is no evidence for their false allegations and that pursuing such a partisan stunt will ‘backfire.'”

Garland and the two IRS whistleblowers — supervisory agent Gary Shapley and case agent Joseph Ziegler — disagree over whether then-U.S. Attorney David Weiss had the ultimate authority to bring charges in the five-year probe.   

In June, Garland had said that Weiss would be able “to make a decision to prosecute any way in which he wanted to and in any district in which he wanted to.”

But in August, Garland said Weiss had informed him that his investigation had reached a stage where he believed his work should continue as special counsel, and he then asked for the designation. Garland said he concluded it was “in the public interest” to appoint Weiss special counsel, giving him expanded powers to continue the probe, in light of the “extraordinary circumstances” of the case.

Since the whistleblowers’ testimony in July, the House GOP-led Ways and Means Committee has also subpoenaed two senior IRS officials with direct knowledge of the October 2022 meeting during which IRS whistleblower Shapley alleged Weiss had said he did not have the ultimate authority to bring charges and had been denied special counsel status. 

The Republican chairman of the committee, Rep. Jason Smith, sent letters to Michael Batdorf, identified as an IRS director of field operations, and Darrell Waldon, an IRS special agent in charge, asking them to appear for transcribed interviews in early September.

Smith said in the letter that the committee wanted to speak with them because of their “direct knowledge of a key meeting on October 7, 2022, in which updates about the Hunter Biden investigation were discussed.” He went on to note that the IRS officials had so far “refused to voluntarily cooperate” with the request for a transcribed interview, so they were therefore being subpoenaed. According to a transcript of Shapley’s May interview before the House Ways and Means Committee, he testified that the Oct. 7, 2022, session had been his “red-line” meeting.

Shapley said Weiss and “senior-level managers” from the IRS, FBI and the Delaware U.S. attorney’s office participated, among others. At the meeting, Shapley alleged that Weiss “surprised us by telling us on the (Hunter Biden) charges, quote: ‘I’m not the deciding official on whether charges are filed,’ unquote. He then shocked us with the earth-shattering news that the Biden-appointed D.C. U.S. Attorney Matthew Graves would not allow him to charge in Washington, D.C., where Hunter Biden lived during some of the years under investigation. To add to the surprise, U.S. Attorney Weiss stated that he subsequently asked for special counsel authority from Main DOJ at that time and was denied that authority.”

Shapley’s testimony included internal IRS communications. “Exhibit 10” is an email exchange between Waldon and Batdorf and Shapley on Oct. 11, 2022. Asked if Shapley’s summary of the Oct. 7, 2022 meeting — including allegations that Weiss said he didn’t have the authority to charge Hunter Biden — was accurate, Waldon responded, “You covered it all.”

The IRS did not immediately respond to CBS News’ request for comment. A spokesperson for Weiss in Delaware and the Justice Department declined to comment.  However, in court documents, Weiss has indicated the investigation is ongoing.   

When the subpoenas were issued last week, the spokesperson for the committee’s Democrats accused the majority of “cherry-picking to build a politically-expedient narrative.” 

“The Committee has a duty to seek the whole truth related to these allegations, and when more than 59 individuals have relevant information, sending two subpoenas is premature,” the spokesperson added.

When the House returns in September, the GOP aide said conference members will come together to discuss a potential impeachment inquiry, which is among the top issues they’ll be discussing. Also high on that list is government spending. Funding for the government expires at the end of September, and if Congress fails to pass a stopgap bill, there would be a government shutdown.

If that were to occur, any government work that is not deemed essential would come to a halt. But congressional committee work to try to get appropriations bills through Congress would continue because that would fall into the category of essential work. But investigations in the House and Senate would come to a halt while the government is shut down.

House Speaker Kevin McCarthy said on Fox News’ “Sunday Morning Futures,” that if the government shuts down, then so would GOP-led investigations. The assessment may incentivize some House Republicans keen on moving forward with any impeachment inquiry to support short-term funding to keep the government running.

John Nolen and Kathryn Watson contributed to this report.