A Democratic senator on Saturday accused President Bush and congressional Republicans of hindering his party's attempts to chart a new course in Iraq even though U.S. troops are fighting violence "they cannot possibly resolve."

Sen. Bob Casey, D-Pa., said increased troop levels ordered earlier this year to give Iraqi politicians breathing space to meet political and diplomatic goals have not had the intended result.

"That means our troops are fighting for a peace that we seem more interested in achieving than the Iraqi politicians do themselves," Casey said while delivering the Democrats' weekly radio address.

The White House has said there have been positive developments in Iraq, such as a reduction in violence and increased economic capacity.

On Friday, Senate Republicans blocked a $50 billion Democratic bill that would have paid for several months of combat. It also would have ordered troop withdrawals from Iraq to begin within 30 days and set a goal of ending combat in December 2008.

Democrats now plan to sit on Bush's $196 billion request for war spending until next year, which pushes the Pentagon toward an accounting nightmare.

Bush has said Congress should not be telling military leaders what to do.

Casey said the war is costing Americans at all levels. More than 3,800 U.S. troops have died in Iraq — 178 from his home state of Pennsylvania. Congress' Joint Economic Committee estimated this week that about $1 trillion has been spent on the war, he said.

About 170,000 troops will spend Thanksgiving in Iraq, he said.

"They will face hatred they did not create and sectarian violence they cannot possibly resolve," Casey said. "They are doing a remarkable job, a heroic job, but the Iraqi leaders are not holding up their end of the bargain."