An IRS special agent is seeking whistleblower protection to disclose information about what the agent alleges is mishandling of an investigation into President Joe Biden’s son, Hunter Biden, according to a letter sent to members of Congress.

Mark Lytle, the attorney for the IRS whistleblower, wrote to lawmakers Wednesday that his client has information about a “failure to mitigate clear conflicts of interest in the ultimate disposition” of a criminal investigation related to the younger Biden’s taxes and whether he made a false statement in connection with a gun purchase.

“Despite serious risks of retaliation, my client is offering to provide you with information necessary to exercise your constitutional oversight function and wishes to make the disclosures in a nonpartisan manner to the leadership of the relevant committees on both sides of the political aisle,” Lytle said in a letter, obtained by The Associated Press, that was sent to the chairmen and ranking members of several House and Senate committees.

The letter states that the supervisory special agent previously disclosed the information they are seeking to share with Congress internally with the IRS and a watchdog for the Justice Department. Lytle added that his client is able to contradict sworn testimony to lawmakers “by a senior political appointee.” That appointee is not named.

The special agent also wants to disclose “examples of preferential treatment and politics improperly infecting decisions and protocols that would normally be followed by career law enforcement professionals in similar circumstances if the subject were not politically connected,” the lawyer added.

“The president respects the rule of law and the independence of the Department of Justice,” White House press secretary Karine Jean-Pierre said during a briefing Thursday. The Justice Department declined to comment. Hunter Biden’s legal team had no immediate comment. A request for comment from the IRS was not immediately returned.

Hunter Biden’s taxes and foreign business work have been under federal investigation by a federal grand jury in Delaware since at least 2018. So far no charges have been filed. Additionally, his membership on the board of a Ukrainian energy company and his efforts to strike deals in China have long raised questions by Republicans about whether he traded on his father’s public service.

Joe Biden has said he has never spoken to his son about foreign business. There are no indications that the federal investigation involves the president.

Attorney General Merrick Garland said in a congressional hearing last month that he won’t interfere with the department’s investigation.

He told the Senate Judiciary Committee that he has left the matter in the hands of U.S. Attorney David Weiss, the top federal prosecutor in Delaware, who would be empowered to expand his investigation outside the state if needed.

“He has been advised he is not to be denied anything he needs,” Garland said. “I have not heard anything from that office to suggest that they are not able to do everything the U.S. Attorney wants to do.”

The whistleblower letter, first reported by The Wall Street Journal, comes as House Republicans have opened their own investigations into nearly every facet of Hunter Biden’s business dealings, including examining foreign payments and other aspects of his finances.

Rep. James Comer, R-Ky., the chairman of the House Oversight Committee, recently reviewed financial transactions by members of the Biden family that were flagged for attention. Those financial reports are routine, with larger financial transactions automatically flagged to the government, and are not evidence on their own of misconduct.

But Comer, who has been leading the various probes into Hunter Biden, said the whistleblower letter is further evidence of the importance of congressional inquiry into the president and his family.

“It’s deeply concerning that the Biden Administration may be obstructing justice by blocking efforts to charge Hunter Biden for tax violations,” Comer said in a statement Thursday.