The Illinois senator called a second news conference of the day Thursday to address the Republican criticism of him and resulting questions about where he stands on Iraq.
He said what he learns from military commanders on his upcoming trip to Iraq will refine his policy -- but "not the 16-month timetable" for withdrawing U.S. troops from combat in Iraq. He said what he learns could affect how many residual troops might be needed to train the Iraqi army and police.
"I am going to do a thorough assessment when I'm there," he told reporters on the airport tarmac here. "I'm sure I'll have more information and continue to refine my policy."
During his presidential campaign, Obama has gone from the hard-edged, vocal opposition to Iraq that defined his early candidacy to more nuanced rhetoric that calls for a phased-out drawdown of all combat brigades that, at a rate of one or two a month, could last 16 months. He has said that if al Qaeda builds bases in Iraq, he would keep troops either in the country or the region to carry out "targeted strikes."
Republicans, who have been goading Obama to return to Iraq to see conditions for himself, pounced.
"There appears to be no issue that Barack Obama is not willing to reverse himself on for the sake of political expedience," said Alex Conant, a spokesman for the national Republican Party. "Obama's Iraq problem undermines the central premise of his candidacy and shows him to be a typical politician."
Obama's GOP rival,, has been a vocal supporter of the Iraq war and war policy has been a central disagreement between the two candidates.
But Obama insisted that his position has not changed at all.
He said he is saying now what he always has: The war was a mistake and needs to be brought to "a responsible end," but "we need to be as careful getting out as we were careless getting in." This means, he said, that his 16-month timeline "was always premised on" not endangering either U.S. troops or Iraq's stability, which he had previously been told by commanders was possible.
"I'm going to continue to gather information to see whether those conditions still hold," he said. "My goal is to end this conflict as soon as possible."
Obama's Web site contains this direct promise about Iraq: "Obama will immediately begin to remove our troops from Iraq. He will remove one to two combat brigades each month, and have all of our combat brigades out of Iraq within 16 months. Obama will make it clear that we will not build any permanent bases in Iraq. He will keep some troops in Iraq to protect our embassy and diplomats; if al Qaeda attempts to build a base within Iraq, he will keep troops in Iraq or elsewhere in the region to carry out targeted strikes on al Qaeda."
Although he did not specifically mention his 16-month timeline on Thursday, Obama called it "pure speculation" to suggest he has been softening or even backing off his position as violence lessens in Iraq.
"I continue to believe that it is a strategic error for us to maintain a long-term occupation in Iraq at a time when conditions in Afghanistan are worsening, al Qaeda is continuing to establish bases in areas of northwest Pakistan, resources there are severely strained and we are spending $10 to $12 billion a month in Iraq that we desperately need here at home, not to mention the strains on our military," Obama said.
But for Obama, appearing to take two positions on one issue is not confined to Iraq, reports CBS News correspondent Dean Reynolds.
Last year, he opposed the Foreign Intelligence Surveillance act because it bestowed retroactive immunity on telecommunications companies that gave the government data on callers. But last week, Obama endorsed a bill doing just that-suggesting security trumps privacy.
And of course, there is Obama's switch on federal financing for elections, which he once supported.
Obama plans a visit this summer to Jordan, Israel, Germany, France and the United Kingdom. The Illinois senator also has said he intends to visit Iraq and Afghanistan this summer as part of an official congressional trip that would be separate from the campaign-funded Mideast and European tour. It would be his second trip to Iraq.
Obama senior foreign policy adviser Susan Rice told reporters on a conference call that Obama would keep to his commitment to begin removing U.S. forces from Iraq "from the early days of his administration." She said the 16-month timeline was based on "the best military advice that he has received" and that it appears to continue to be "still broadly applicable."
"Obviously if there are fewer brigades or more brigades" there by the time a new administration takes office next year, she said, "that would adjust the timeline."
Obama's position has been that troops should only remain in Iraq to protect the U.S. embassy, engage in humanitarian efforts, and conduct counterterrorism operations. She said Obama would consider having the U.S. continue to train Iraqi police forces if they show some progress, "but he's not interested in training one sector of Iraqi society to kill another."
McCain was an early supporter of increasing the number of U.S. troops in Iraq as President Bush did last year. He wants to pursue the current counterinsurgency tactics to give Iraqis time to work out a political reconciliation. He has said he's willing to see some U.S. troops stay there as much as 100 years but not if they are being wounded or killed in combat. Rather he supports keeping a military presence in that part of the world because of its volatility.