White House says Obama unaware of job offer to Colo. candidate

"But Romanoff said that he was committed to the Senate race and no longer interested in working for the administration, and that ended the discussion," Gibbs said.

Sestak also declined his offer, and he defeated Sen. Arlen Specter late last month. He said last week he had rejected Clinton's feeler in less than a minute.

The revelations about the administration's political dealings come at the start of former Illinois Gov. Rod Blagojevich's trial on charges of scheming to profit from his ability to fill Obama's old Senate seat. Blagojevich, 53, has pleaded not guilty to 24 counts including racketeering, wire fraud, attempted extortion and bribery. He has denied scheming to sell or trade the Senate seat for personal gains.

Obama's top aides -- Emanuel and Valerie Jarrett -- were subpoenaed to testify about their role in picking Obama's replacement during private phone calls; no one from Obama's administration has been charged with wrongdoing.

Early on his presidency, Obama tapped a potential 2012 rival, Utah Gov. Jon Huntsman, for the U.S. ambassadorship to China. Huntsman was nominated in May 2009 and confirmed last August.

In a two-page report on the Sestak case, the White House counsel said the administration did nothing illegal or unethical. Republicans weren't appeased.

"Just how deep does the Obama White House's effort to invoke Chicago-style politics for the purpose of manipulating elections really go?" Rep. Darrell Issa asked on Wednesday. Issa is seeking internal White House documents about its political operations in specific races.

Bennet has outpaced Romanoff in fundraising and support from Washington, although party activists attending the state party assembly last month favored the challenger by a margin of 60 percent to 40 percent. The primary is Aug. 10.

Bennet was appointed by Gov. Bill Ritter to fill out the final two years of the term of Ken Salazar, who resigned to become interior secretary.