Over the last eight years, most Democratic politicians have made a distinction between the Good War (Afghanistan) and the Bad War (Iraq).

That very much includes Barack Obama. As an Illinois state senator, he spoke out against military action in Iraq in 2002, and as a U.S. senator at a September 2007 hearing, he offered a blisteringly negative assessment of Iraq so lengthy that it left no time for Gen. David Petraeus to reply.

But he has always said he supported military action in Afghanistan as a valid response to the Sept. 11 attacks, which were planned there.

So it is a little surprising to see in the results of this month's ABC/Washington Post poll that most American voters are not making the Good War/Bad War distinction.

Has the war in Afghanistan contributed to the long-term security of the United States? Some 53 percent say it has, while 44 percent say it hasn't.

Has the war in Iraq contributed to the long-term security of the United States? About 50 percent say it has while 48 percent say it hasn't.

Those are virtually identical numbers. It seems that about half of Americans think both were Good Wars and about half consider them both Bad Wars.

Substantial majorities of Republican voters consider both to be wars worth fighting, while majorities of Democratic voters disagree.

What's most interesting is the switch among Democratic voters. A year ago 41 percent of them thought Afghanistan was worth fighting for, while only 12 percent felt that way about Iraq. In this month's polls, the corresponding numbers were 36 percent and 29 percent. The Good War/Bad War distinction is disappearing.

One reason for this is that things have been going pretty well in Iraq while things in Afghanistan look dicey. The ABC/Post poll reported that 71 percent of Americans oppose immediate withdrawal from Iraq and 60 percent favor keeping 50,000 noncombat troops in Iraq in a supporting role. Keeping U.S. troops there seems hardly more controversial than keeping them in Germany.

But there is something more fundamental here. The Good War/Bad War distinction was based in large part on the argument that George W. Bush lied about Saddam Hussein's possession of weapons of mass destruction.

Of course Bush didn't lie. He relied on the same intelligence that many Democrats and leaders of foreign nations did. But, as Karl Rove wrote in his Wall Street Journal column this week, the Bush White House never pushed back against the Bush Lied claim when it was advanced by prominent Democrats like Edward Kennedy, John Kerry, John Edwards and Al Gore.

This was, as Rove now concedes, "a dagger aimed at [the] administration's heart." It tended to delegitimize the Iraq war and encouraged many Democrats to wish for their country's defeat. No wonder that as late as July 2009 only a handful of Democrats considered Iraq a war worth fighting.

Now that Obama has been commander in chief for 18 months, Democrats are singing a different tune. They no longer have a psychological stake in believing that Bush's surge strategy failed, as Democrats like Harry Reid and Barack Obama insisted in 2007 and 2008.

They are coming to grips with the reality that our mission in Iraq is succeeding, that a reasonably functional democracy is emerging, and that there is no great peril in maintaining a military presence there.

At the same time, the dovish instincts that have been such a prominent part of Democrats' DNA since they recoiled from Lyndon Johnson's Vietnam War are apparent in their assessment of the war in Afghanistan.

Obama's decision last December, after a three-month review, to seek something like victory there is still supported by most Republican voters, but after negative developments many Democratic voters are turning against the president's policy. Increasingly they regard Afghanistan as a Bad War.

Some Republican politicians are tempted to seek political gain from this. Thus Republican National Committee Chairman Michael Steele on July 1 told Republican candidates they should call Afghanistan "Obama's war."

In some areas of life, turnabout is fair play. But not in war. Prominent Democrats may have been happy to delegitimize the Iraq war, but that's not a good reason for Republicans to do something similar on Afghanistan. Rooting for your country's defeat is ignoble. More important, when it comes your turn to take responsibility, it can be self-defeating.

Michael Barone, The Examiner's senior political analyst, can be contacted at mbarone@washingtonexaminer.com. His columns appear Wednesday and Sunday, and his stories and blog posts appear on ExaminerPolitics.com.