07/13/2008 05:12 am ET Updated May 25, 2011

Note to Obama... Don't Go Soft on Iraq!

On this site, Arianna Huffington was the first to warn Barack Obama that he would disappoint a lot of his enthusiastic supporters, and not necessarily gain any new ones, by moving too fast to the center. Apparently, he wasn't listening.

He started out safely enough: renouncing a pledge to take public financing. No big deal. He moved on to more serious matters: letting states decide when to apply the death penalty to child rapists and supporting an individual's right to own a handgun. Issues on which Democrats can honestly disagree. Then he reversed course on providing immunity to phone companies who joined George Bush's wiretapping blitz. Why? Especially when he publicly promised not to?

Still, those were not issues central to the campaign. Obama could shift positions on such secondary issues, most observers agreed, as long as he didn't waffle on the war. Uh-oh. Guess what? He just did.

Speaking to reporters upon arriving in Fargo, N.D., Obama said he was looking forward to meeting military commanders when he visits Baghdad later in the summer and, based on what he learned, might "refine his policies" on Iraq.

Oh, no. Say it isn't so. Obama didn't win the primaries by being fuzzy on Iraq. He generated so much excitement and support principally because he was out front, opposing the war in Iraq from the very beginning, while Hillary Clinton, John Edwards, Joe Biden and others were voting for it. More than any other issue, opposition to the war in Iraq defines Obama's candidacy. He can't go soft on Iraq.

To his credit, Obama quickly moved to clarify his statement. He repeated his determination to end the war and to start bringing homes immediately at the pace of what he hopes will be one or two brigades a month - by which schedule all American troops would be out of Iraq in 16 months. There was, Obama insisted, no change in his position.

And in fact, during the primaries, Obama repeatedly expressed the caution (perhaps lost on his supporters) that how quickly we could pull troops out of Iraq would depend on conditions on the ground. As he put it so artfully: "We have to be as careful getting out, as we were careless going in."

Still, the damage is already done. Perception, too often, is reality. To hear Obama say he's open to "refining" his policies on Iraq is enough to inject joy into the McCain campaign and fear into the heart of every Democrat.

The 2008 election will be won or lost on two issues: the economy and the war.

On the war, McCain and Obama have been polar opposites. Obama wants to end it, McCain wants to carry it on. Obama wants to start bringing troops home immediately, McCain says the earliest we could bring troops home is 2013. Obama wants all troops home by 2013, McCain doesn't mind if we stay in Iraq another 100 years.

The differences are clear and must remain that way. Iraq is a winning issue for Democrats. As long as Obama doesn't muddle toward the middle.