(CNN) - New Mexico Gov. Bill Richardson spoke out foir the first time since withdrawing his nomination as secretary of commerce, citing the distraction of a federal investigation into ties to a company that has done business with his state.
Speaking to reporters Monday, he said that he underestimated how long the investigation would take, calling it an "untenable delay" likely to hinder his confirmation process.
Watch: Richardson speaks out
Two Democratic officials told CNN the investigation involves a California company that won municipal bond business in New Mexico after contributing money to various Richardson causes.
In a statement released Sunday afternoon, Richardson said, "Let me say unequivocally that I and my (gubernatorial) administration have acted properly in all matters and that this investigation will bear out that fact. But 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," Richardson added.
In his own statement, President-elect Barack Obama said it was "with deep regret" that he had accepted Richardson's decision to withdraw.
"Governor Richardson is an outstanding public servant and would have brought to the job of Commerce Secretary and our economic team great insights accumulated through an extraordinary career in federal and state office," Obama said.
"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."
Obama did not elaborate on picking a new nominee for secretary of commerce, saying only, "We must move quickly to fill the void left by Governor Richardson's decision (and) I look forward to his future service to our country and in my administration."
"Yesterday I was hurting over this decision. I lost a cabinet appointment," he told reporters Monday.
"But I think we have to focus on what people are losing in this country," he said, referencing heightened U.S. unemployment. "Mine is minor compared to that," he said.
Richardson did not offer details of the current investigation or the company involved, saying only that "a pending investigation of a company that has done business with New Mexico state government promises to extend for several weeks or, perhaps, even months."
He said in a statement that he will continue as governor of New Mexico.
Meanwhile, two Democratic strategists outside the transition told CNN that Obama aides pushed the withdrawal because they did not want another ethical distraction in the wake of controversy surrounding embattled Illinois Gov. Rod Blagojevich. Federal prosecutors charge that Blagojevich had hoped to barter Obama's Senate seat for either money or influence.
One of these Democrats described Richardson as "stunned" by the sudden turn of events. But Democrats who talked with CNN noted it was in keeping with the Obama philosophy of resolving issues quickly.
New Mexico Lt. Gov. Diane Denish issued a statement Sunday, saying, "Governor Richardson postponed taking a position in the administration to ensure that President Obama and the American people face no delays in getting to work to fix our ailing economy ... In the meantime, Governor Richardson and I will work together, as we have over the last six years, to tackle challenges at home, to craft a workable budget with the legislature and to strengthen our economy to make sure that every New Mexico family has the opportunity to succeed."
Richardson, 61, is one of the best-known Hispanics in the Democratic Party, and served as energy secretary in the Clinton administration as well as ambassador to the United Nations.
– CNN's Ed Henry contributed to this report.