WASHINGTON - New Mexico Gov. Bill Richardson withdrew yesterday as the nominee for commerce secretary, saying a federal probe that has reached into his office could last months and was certain to bog down his confirmation.

Richardson, who intends to remain governor, became President-elect Barack Obama's first failed cabinet nominee even before the first confirmation hearings, expected to begin this month. Obama said he would move quickly to fill the position.

In a statement yesterday, Richardson said "unequivocally" that he and his administration "have acted properly in all matters and that this investigation will bear out that fact."

But, he added, "I have concluded that the ongoing investigation also would have forced an untenable delay in the confirmation process. Given the gravity of the economic situation the nation is facing, I could not in good conscience ask the president-elect and his administration to delay for one day the important work that needs to be done."

It was not clear whether Richardson's decision had been prompted by a new finding in the probe or a change of heart by Obama's team or Senate Democrats preparing confirmation hearings.

Reports of an investigation into possible pay-to-play actions by a California firm that did business with New Mexico surfaced in mid-December, after Obama had tapped Richardson. As recently as last week, Democratic and Republican aides were preparing for his confirmation hearing to go forward.

A federal grand jury is looking into how CDR Financial Products, which gave $100,000 to Richardson political committees, got $1.5 million in state contracts in New Mexico.

Obama campaigned last year on promises to reduce corruption and the influence of special interests in Washington.

He said in a statement that he looked forward to Richardson's "future service to our country and in my administration," and that "it is a measure of his willingness to put the nation first that he has removed himself as a candidate for the cabinet in order to avoid any delay in filling this important economic post at this critical time."

Richardson, a former U.N. ambassador and energy secretary under President Bill Clinton, was among Obama's early opponents for the Democratic presidential nomination. After dropping out, he joined Obama's camp, endorsing him over Sen. Hillary Rodham Clinton.