Washington ? An ex-aide to Commerce Secretary nominee Judd Gregg is under investigation for allegedly taking baseball and hockey tickets from a lobbyist in exchange for legislative favors.

The revelation comes at a particularly bad time for President Barack Obama’s administration, a day after he had to defend his selection process because two high-profile nominees withdrew due to tax problems.

It also points to the challenges confronting a president who promised to end Washington’s insider dealings but who has hired mostly Washington insiders.

White House spokesman Robert Gibbs said Wednesday that Gregg “is neither a target nor a subject” of the investigation, and he noted the aide in question stopped working for Gregg four years ago.

Gregg, a Republican senator from New Hampshire, acknowledged in a statement that former aide Kevin Koonce is being investigated for actions that took place while Koonce worked for him. Prior to Gregg’s statement, The Associated Press reported that Koonce was “Staffer F” in court documents filed as part of the Jack Abramoff lobbying scandal.

The senator said he was unaware of the investigation until he was contacted by the Justice Department.

“Prior to this, I was not aware of any improper acts by the former staffer in question. He left my office more than four years ago due to issues completely unrelated to those brought to light by this investigation,” Gregg said.

Gregg said he had received written notice that he is neither a subject nor a target of the investigation, and he added his office “welcomes the opportunity to be helpful.”

Staffer F was cited in a guilty plea last week by Todd Boulanger, a former deputy to Abramoff. In federal court, Boulanger admitted he plied the staffer with front-row tickets to a hockey game, meals and drinks and other tickets to a baseball game, and in exchange received favors in spending legislation.

The total value of the gifts Staffer F took from Boulanger exceeded $10,000, court papers said.