WASHINGTON (CNN) -- Sen. Barack Obama on Thursday criticized a recent vote by Democratic presidential rival Sen. Hillary Clinton as helping to give President Bush a "blank check" to take military action against Iran.
Sen. Barack Obama says Sen. Hillary Clinton has shown "flawed" judgment.
"We know in the past that the president has used some of the flimsiest excuses to try to move his agenda regardless of what Congress says," Obama said in an interview with CNN's Wolf Blitzer.
Last month, Clinton voted to support a resolution declaring Iran's Islamic Revolutionary Guard Corps, an elite part of the Iranian military, a foreign terrorist group. (The nonbinding amendment to the Defense Authorization Act passed by a 76-22 vote.)
Obama said he would have voted against the measure but didn't because he was campaigning in New Hampshire at the time. He said it was impossible to know when votes will be scheduled in the Senate. "This is a problem" related to running for president, he said.
Obama said Clinton also had shown "flawed" judgment during the vote to authorize the Iraq war five years ago.
"We know that there was embodied in this legislation, or this resolution sent to the Senate, language that would say our Iraqi troop structures should in part be determined by our desire to deal with Iran," Obama said. "Now if you know that in the past the president has taken a blank check and cashed it, we don't want to repeat that mistake."
Clinton on Thursday defended her vote on the resolution during an interview on New Hampshire Public Radio, saying "what I voted on was a nonbinding resolution. It's not an amendment. It's not a law."
While Clinton was campaigning Sunday in New Hampton, Iowa, an audience member at a town hall-style meeting pressed her on why she voted for the Iran measure and asked why she hadn't learned from past "mistakes." Calling "the premise of the question" wrong, the senator from New York argued the resolution calls for the terrorist label so that sanctions can be imposed.
The sanctions, Clinton said, will in turn "send a clear message to the leadership" and lead to stronger diplomatic efforts.
Earlier this month, Clinton also co-sponsored legislation with Sen. Jim Webb, D-Virginia, that would prohibit military operations against Iran without congressional approval.
Obama's comments came on the fifth anniversary of the 77-23 Senate vote that authorized the president to use force against Iraq. Obama, then an Illinois state senator, spoke out against the resolution authorizing force at the time.
Clinton's 2002 vote shows a clear difference in judgment between the two of them, Obama said. Watch as Obama questions Clinton's judgment »
"I don't think it disqualified her, but I think it speaks to her judgment and it speaks to my judgment," Obama said. "It speaks to how we will make decisions going forward.
"I think her judgment was flawed on this issue."
Obama said he also will step up efforts to clarify his differences with Clinton, whom many political observers view as the front-runner for the Democratic nomination.
"There's no doubt we are moving into a different phase of the campaign," Obama said. "The first part of a campaign is to offer some biography and give people a sense of where I've been and what I am about.
"In this next phase, we want to make sure that voters understand that on big issues, like the decision to go into the war in Iraq, I had real differences with the other candidates, and that reflects on my judgment."
Another leading Democratic candidate, John Edwards, also voted in 2002 to authorize force in Iraq while he was then a senator from North Carolina. He later called his vote a mistake.
In a veiled swipe at Clinton, Obama also suggested he could better unite the country and offer "something new, as opposed to looking backward and simply duplicating some of the politics that we've become so accustomed to, that frankly the American people are sick of."
Obama would not say whether he would consider Clinton as his running mate should he become the Democratic Party's nominee.
"I think Sen. Clinton is a very capable person," he said. "Right now, my goal is to make sure I am the nominee, and she is still the senator from New York." E-mail to a friend
CNN's Scott Anderson and Alexander Mooney contributed to this report.