Sestak said last month that the White House offered him a high-ranking federal job to forego a primary challenge to Sen. Arlen Specter (D.,Pa.), but Sestak has since declined to provide details. The top Republican on the House Government Oversight and Reform Committee, California's Darrell Issa, has demanded answers from the White House, saying that somebody broke the law if such an offer was made.

Issa, in a television interview Monday, accused the White House of a "Nixonian" cover-up of Sestak's allegation.

"I'm told that whatever conversations have been had are not problematic," Gibbs said in response to questions during his daily briefing of the White House press. He said he had "talked to several people in the White House...I've talked to people that have talked to others in the White House."

Gibbs, asked if the White House counsel had investigated whether the contact was criminal, declined to answer.

"I think that Congressman Sestak has said that this - whatever happened is in the past, and he's focused on his primary election," Gibbs said.

The explanation was not sufficient for Issa, who demanded in a formal letter that White House counsel Robert Bauer disclose all contacts any officials had with Sestak.