WASHINGTON – While the rest of us enjoyed our holiday, 10 more Americans were killed in Iraq on Memorial Day – adding to the human toll of that accursed war.

This summer threatens to bring more such grim days, as the expanded ground forces move deeper into Baghdad neighborhoods while terrorists plant their diabolical explosive charges along the roads in outlying provinces where they know U.S. convoys will pass.

But the end is coming into view – not soon enough to spare every precious life, but sooner than President Bush and Vice President Cheney may wish.

The dynamic in Congress has been set in motion that will bring this war to an end – or, at least, reduce the scale of American involvement and redefine the mission for U.S. troops.

The promised September evaluation from Gen. David Petraeus, the widely trusted American commander in Iraq, will be one trigger for action. He will report on the success of the “surge” strategy, and if present indications hold, he will say the military has achieved some objectives but Iraqi politics are still stuck in neutral, with sectarian divisions blocking needed reforms.

That will be the setting for a debate on the Pentagon spending bill, a time of decision. And the third trigger – perhaps the most important – will be the imminent approach of the 2008 election campaign.

The position of the Democratic Party in that contest is certain. Last week, 60 percent of the Democrats in the House of Representatives voted against further funding of the war – even with the conditions their leaders had negotiated with the White House. Benchmarks requiring certain actions by the Iraqi government, with penalties in reconstruction aid if Prime Minister Nouri al-Maliki fails to deliver, were not enough to persuade most Democrats to continue the war effort.

The leading Democratic presidential candidates – Hillary Rodham Clinton, Barack Obama and John Edwards – all voted or declared for cutting off the war funding.

Beyond reasonable doubt, the Democrats will campaign in 2008 as the anti-war party – counting on support from a public which, by almost 2-1 margins, now says that attacking Iraq was a mistake and the war should be ended.

The question that remains for the autumn is what will the Republicans do? Their congressional members voted almost unanimously to give the president financing long enough to sustain the current Iraq offensive. All their presidential candidates except libertarian Rep. Ron Paul, who opposed the war from the start, are in lock step with the president.

But just below the surface, the GOP ground is beginning to shift. Few if any Republicans want to go into the 2008 election with 150,000 American troops still under attack in Iraq.

Mitch McConnell, the supremely realistic Republican leader of the Senate, told reporters that “the handwriting is on the wall that we are going in a different direction in the fall, and I expect the president to lead it.”

Bush has hinted that he is taking a fresh look at the suggestion from the Baker-Hamilton Iraq Study Group that U.S. troops be reduced in numbers and redeployed to concentrate on training Iraqis and fighting al-Qaida.

He was cool to that report when it was issued in December, but now he has moved on another of the Baker-Hamilton recommendations by having his ambassador in Baghdad open talks with the Iranian ambassador on the future of Iraq.

Meantime, a significant movement is developing in the Senate to make the Baker-Hamilton recommendations the official policy of the government. A resolution to that effect, co-sponsored by Democratic Sen. Ken Salazar of Colorado and Republican Sen. Lamar Alexander of Tennessee, will be introduced in early June, with at least six other senators – three from each party – endorsing it.

These senators are centrists – the kind that can exert leverage on their colleagues. But the man who can do the most to catalyze the shift among Republicans is Sen. John Warner of Virginia, the widely respected former chairman of the Armed Services Committee. Colleagues say that Warner is torn between his loyalty to the president and his own deep anxiety about the course of events in Iraq. And as a former Navy secretary, he has an acute awareness of the price America’s fighting men and women are paying for the policy mistakes in Iraq.

If Warner shifts, many other Republican senators will move with him, and the policy will change. I think that time is coming soon.

David Broder is a Washington Post columnist. Contact him by writing to davidbroder@washpost.com.