By Sarah N. Lynch

WASHINGTON The federal prosecutor overseeing the criminal case against U.S. President Joe Biden's son Hunter on Monday said the Justice Department never impeded him from bringing charges, appearing to debunk claims made by an Internal Revenue Service whistleblower.

Delaware U.S. Attorney David Weiss in a letter to Republican Senator Lindsey Graham denied allegations that he ever formally sought permission from Attorney General Merrick Garland to be designated as special counsel - a status that would have allowed him to bring federal charges in any district across the nation against Hunter Biden.

"I have not requested Special Counsel designation," wrote Weiss, who was appointed by Republican former President Donald Trump.

"Rather, I had discussions with Departmental officials regarding potential appointment ... which would have allowed me to file charges in a district outside my own without the partnership of the local U.S. Attorney. I was assured that I would be granted this authority if it proved necessary."

Weiss' office last month revealed that it was charging Hunter Biden with two misdemeanor tax charges, to which the president's son is expected to plead guilty later this month. Hunter Biden also has agreed to enter into a pretrial diversion program to avoid facing a more serious felony count of possessing a firearm while he was using illegal drugs.

Republicans have questioned why Weiss did not bring more aggressive felony charges.

Their criticism has been fueled in part by claims from Gary Shapley, an IRS criminal supervisory agent who worked on the Hunter Biden investigation.

Shapley in an interview with lawmakers claimed that the Justice Department repeatedly stonewalled the probe, starting during the Trump administration and continuing through to the present.

Most notably, Shapley said investigators uncovered evidence of more serious tax crimes that could only be pursued in either Washington, D.C., or California, but not in Delaware.

Shapley said that when Weiss sought permission from Garland to be designated as special counsel, so he could bring charges from anywhere in the country, his request was denied.

Garland has denied the claim, telling reporters last month that Weiss made no such request and stating that Weiss was given "complete authority."

Hunter Biden's attorney has also denied that his client received any special treatment.

Weiss, in his letter on Monday, confirmed Garland's prior comments on the case, telling lawmakers he has "never been denied the authority to bring charges in any jurisdiction."

(Reporting by Sarah N. Lynch; Editing by Scott Malone and Peter Graff)