President Obama's latest Cabinet setback -- the sudden withdrawal of Republican Sen. Judd Gregg as commerce secretary nominee -- has put the White House on the defensive, particularly Chief of Staff Rahm Emanuel, whom some critics blame for cracks in the vetting process.

"They need to do a better job in their vetting process," said Kurt Bardella, a spokesman for Rep. Darrell Issa, R-Calif. An administration gets a pass for botching the selection of one nominee, he said, "but the third or fourth time, you have to start asking, are people doing their jobs?"

Gregg's withdrawal came just three weeks into Obama's presidency and on the heels of several other Cabinet troubles. He still needs to fill two vacancies -- at the Commerce and Health and Human Services departments. Former Senate Democratic leader Tom Daschle withdrew his nomination for the latter post amid a tax controversy, while Treasury Secretary Tim Geithner was confirmed by the Senate despite revelations that he had not paid some of his taxes on time.

New Mexico Gov. Bill Richardson was Obama's first choice for commerce secretary. He withdrew in early January following the disclosure that a grand jury is investigating allegations of wrongdoing in the awarding of contracts in his state. Richardson has not been implicated personally.

Obama told FOX News in an interview right after Dascle's withdrawal earlier this month that he takes full responsibility.

"I consider this a mistake on my part, one that I intend to fix and correct and make sure that we're not screwing up again," Obama said.

"Ultimately I have to take responsibility for a process that resulted in us not having a (health and human services) secretary at a time when people need relief on their health care costs."

The troubles come as the new president expends political capital in Washington -- and around the country -- for his economic package and is seeking to move forward with an ambitious agenda in the midst of an economic recession.

Emanuel acknowledged to reporters Thursday that some might question the administration's early competence.

"Some may call it amateur hour," Emanuel said, but he thinks -- given Obama's accomplishments so far -- that the current administration measures up well to the Clinton administration, in which Emanuel worked as a senior adviser from 1993 to 1998.

But Bardella says Emanuel's notorious brand of brass-knuckles politics has contributed to Obama stumbling out of the gate.

"I think what you're seeing is what happens when the rhetoric of your campaign clashes with how you decide to run your operation," he said, claiming that Obama has failed to govern from the center by politicizing the West Wing.

"You do not pick Rahm Emanuel as chief of staff without knowing what kind of politics he will bring in the West Wing."

Emanuel's combative style as political director in the early days of the Clinton administration earned him the nickname "Rahmbo," after the flame-throwing movie character Rambo.

He was elected to Congress in 2002 and quickly became a major power. He wound up overseeing the party's House election efforts in 2006 and helped win a majority for Democrats through tireless fundraising and candidate recruitment.

Doug Schoen, a Democratic consultant and a former adviser to the Clinton White House who worked with Emanuel, said it's hard to defend or attack Emanuel without knowing how involved he's been in the vetting process.

"To criticize the administration directly for an ineffective vetting process makes sense," he said. "To put it all on Rahm doesn't strike me as fair or appropriate."

But Bardella believes Obama, by bringing Emanuel on board to answer critics who thought he wasn't tough enough, underestimated the impact Emanuel would have on his administration.

"In some ways, the different styles complement each other," he said. "Unfortunately, thus far, the different styles have ended up colliding with each other and the results have been bungled nominees."

The Associated Press contributed to this report.