Democrat Barack Obama struggled Thursday to explain how his upcoming trip to Iraq might refine, but not basically alter, his promise to quickly remove US combat troops from the war. A dustup over war policy - one of the main issues separating the Illinois senator from his Republican opponent, John McCain - overshadowed Obama's town-hall meeting here with veterans to talk about patriotism and his plans to care for them. Republicans pounced on the chance to characterize Obama as altering one of the core policies that drove his candidacy "for the sake of political expedience." He denied equally forcefully that he was shifting positions. Arriving in Fargo, Obama hastily called a news conference to discuss news of a sixth straight month of nationwide job losses, but the questioning turned to Iraq policy and his impending trip there. "I am going to do a thorough assessment when I'm there," he said. "I'm sure I'll have more information and continue to refine my policy." He left the impression that his talks with military commanders there could refine his promise to remove US combat troops within 16 months of taking office. Less than four hours later, after the town hall meeting, Obama appeared before reporters for another statement and round of questions to "try this again." "Apparently I was not clear enough this morning," he said. He blamed any confusion on the McCain campaign, which he said had "primed the pump with the press" to suggest "we were changing our policy when we haven't." "I have said throughout this campaign that this war was ill-conceived, that it was a strategic blunder and that it needs to come to an end," he said. "I have also said I would be deliberate and careful about how we get out. That position has not changed. I am not searching for maneuvering room with respect to that position." He promised to summon the joint chiefs of staff on his first day in office "and I will give them a new mission and that is to end this war, responsibly and deliberately, but decisively." He said that when he talked earlier about refining his policy after talking with commanders in Iraq, he was referring not to his 16-month timeline, but to how many troops may need to remain in Iraq to train the local army and police and what troop presence might be needed "`to be sure al-Qaida doesn't re-establish a foothold there." "I will bring our troops out at a pace of one two brigades a month" which would mean the United States would be totally out of Iraq in 16 months, he said. "That is what I intend to do as president of the United States." But later in the session, he said it is possible the 16-month timeline could slip if the pace of withdrawal needs to be slowed some months to ensure troop safety. "I have always said ... I would always reserve the right to do what's best," Obama said. 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 the phased-out drawdown of all combat brigades. He has said that if al-Qaida builds bases in Iraq, he would keep troops either in the country or the region to carry out "targeted strikes." Republicans, who have claimed Obama needs an update on the situation in Iraq, e-mailed a midday broadside. "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." McCain, has been a vocal supporter of the Iraq war and war policy has been a central disagreement between the two candidates. 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.