CHICAGO (AP) -- An IRS whistleblower who testified publicly about investigations into Hunter Biden's taxes is expected to be promoted to IRS acting commissioner, two sources familiar with the plan tell The Associated Press.

Gary Shapley, an IRS employee who testified to Congress as Republicans reviewed the business dealings of Joe Biden's son, said he was retaliated against for cooperating in the investigations. In March, Shapley was promoted to Deputy Chief of IRS Criminal Investigations, and another IRS investigator who testified about Biden's taxes, Joseph Ziegler, was assigned to the Treasury Secretary's office as a senior adviser for IRS reform.

Now, the tax collection agency is planning to name Shapley to one of the highest-ranking roles at the agency -- in an interim role -- as former Missouri congressman Billy Long awaits a confirmation hearing to lead the agency permanently, the people say. They were not authorized to speak publicly about the plan.

President Donald Trump nominated Long, who worked as an auctioneer before serving six terms in the House of Representatives, to serve as the next commissioner of the IRS.

Shapley replaces Melanie Krause, who is resigning from her role as acting IRS commissioner over a deal to share immigrants' tax data with Immigration and Customs Enforcement to identify and deport people illegally in the U.S.

CNN originally reported the news about Shapley's new role. A representative from the IRS did not respond to an Associated Press request for comment.

Shapley and Joseph Ziegler say they were removed from the Hunter Biden case in December 2022 after they told their bosses that the Justice Department and former Delaware U.S. Attorney David Weiss had engaged in a pattern of "slow-walking investigative steps" and delaying enforcement actions in the months before the 2020 presidential election won by Democrat Joe Biden.

The investigation into Hunter Biden ended with Joe Biden pardoning his son, sparing the younger Biden a possible prison sentence for federal felony gun and tax convictions and reversing his past promises not to use the extraordinary powers of the presidency for the benefit of his family.

Hunter Biden had been set to stand trial last September in the California case accusing him of failing to pay at least $1.4 million in taxes. But he agreed to plead guilty to misdemeanor and felony charges in a surprise move hours after jury selection was set to begin.

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