"The president has confidence in the system," Press Secretary Robert Gibbs said during a news briefing.
Former Sen. Tom Daschle withdrew his name from consideration as Health and Human Services secretary and Nancy Killefer asked that her name be pulled from consideration to be the first U.S. chief performance officer -- both because of tax issues.
"I'm not going to spend time looking through the rear-view mirror," Gibbs said after expressing the administration's confidence in the vetting process several times. "The president understands each served with the distinction."
Gibbs said Daschle made the decision to withdraw and "did not get a signal" from the White House.
Daschle and Killefer asked Obama to withdraw their nominations, Gibbs said, and "each also decided they couldn't distract from the agenda he was pursuing."
When questioned about Obama's pledge that he would usher in "an era of responsibility" and whether anyone in the administration accepted responsibility for the lapses in the vetting, Gibbs said, "We all take responsibility. The president takes responsibility."
He said the difference between the situation between Daschle and Killefer and the confirmation of Tim Geithner as treasury secretary came because in Geithner's situation, "the process worked."
Reports surfaced that Geithner also owed -- and repaid -- taxes and Gibbs did not directly answer questions about why Geithner's tax situation differed from Killefer's and Daschle's problems.
The selection of a defense lobbyist for a Pentagon post and a Goldman-Sachs advocate to the Treasury Department also raised eyebrows. The appointment of George Mitchell, who ran a lobbying firm, as Middle East special envoy, also provoked questions since his firm spoke in Washington on behalf of several Middle Eastern concerns.
Gibbs said the administration "is looking for replacements as we speak."