On the deadliest day of the Iraq war this year, President Bush told newly empowered House Democrats today there are limits to how long the United States will stay committed to the bloody conflict.

"I have made it clear to the Iraqi government just as I have made it clear to the American people: our commitment is not open ended," Bush said, speaking at the House Democratic Caucus meeting in Williamsburg. He did not elaborate or offer a timetable for withdrawal of U.S. troops.

Bush spoke as the death toll from a car bombing{vbar}http://www.washingtonpost.com/wp-dyn/content/article/2007/02/03/AR2007020300410.html in a Baghdad market today was approaching 100 with reports of more than 200 injuries.

In a rare presidential trip to an opposition-party summit, Bush told the House Democrats that his plan to send 21,500 additional troops to Iraq "has caused a lot of debate." Lawmakers from both parties are debating what to say in a nonbinding Senate resolution that will oppose the plan.

The Democrats invited Bush to their retreat one month after their party took control of Congress and two days before the president will submit a budget for the fiscal year that begins Oct. 1.

Some Democrats called the visit a sign Bush is willing to work with the opposition. But many remained skeptical, given his determination to order more troops to Iraq, where 132,000 U.S. service members already serve.

Striking a bipartisan tone, Bush called House Speaker Nancy Pelosi (D-Calif.) a "fine woman" and Majority Leader Steny H. Hoyer (D-Md.) a "down-to-earth, no-nonsense guy." He then suggested that Democrats share many of his goals.

"These are tough times and yet there's no doubt in my mind that you want to secure this homeland just as much as I do," Bush said. "You remember the lessons of September the 11th just like I do. And you understand a fundamental obligation of government is to do everything in our power to protect people here. And I'm looking forward to working with you on that,"

Bush's appearance followed the release yesterday of a U.S. intelligence community report that offers a bleak assessment{vbar}http://www.washingtonpost.com/wp-dyn/content/article/2007/02/02/AR2007020200685.html of the situation in Iraq. The latest National Intelligence Estimate warns that deepening sectarian divisions in the country could destroy the government and lead to anarchy, partition or the emergence of a new dictatorship.

Bush said his new plan for the war, which has claimed the lives of more than 3,000 U.S. service members and tens of thousands of Iraqi civilians, was devised after careful consultation with military leaders and lawmakers from both parties.

"I took a lot of time thinking about how best to achieve an objective of a country governing and sustaining and defending itself, a country that will be an ally on this war on terror," Bush said, adding that he "came up with a plan that I generally believe has the best chance of succeeding."

But Democratic leaders called the National Intelligence Estimate fresh evidence that Bush's policies have failed.

"Rather than commit more U.S. troops to a struggle that is the responsibility of the Iraqis to resolve, our emphasis should be on working with Iraq's leaders and Iraq's neighbors to produce the kind of political and diplomatic breakthroughs that offer the best chance to stop the violence," Pelosi said in a statement yesterday.

Senate Majority Leader Harry M. Reid (D-Nev.) said the report "appears to be the latest in a long line of bleak assessments by foreign policy and military experts indicating the President's plan is flawed and failing."

Earlier today, Bush said in his weekly radio address that his top priority in submitting a budget "will continue to be keeping America safe and winning the war against extremists who want to destroy our way of life."

"The budget I will submit to Congress includes the cost of funding the global war on terror, including in Iraq and Afghanistan," Bush said. "Our troops deserve our full support, and this budget gives them the resources they need."

On Monday, Bush plans to ask Congress{vbar}http://www.washingtonpost.com/wp-dyn/content/article/2007/02/02/AR2007020201936_pf.html for close to three-quarters of a trillion dollars in defense spending, $245 billion to cover the cost of fighting in Iraq and Afghanistan and other elements of the "global war on terror," senior administration officials said.

Bush also told his radio audience today that the government must reign in spending on entitlement programs such as Social Security, Medicare and Medicaid.

"Unless we act, we will saddle our children and grandchildren with tens of trillions of dollars of unfunded obligations," he said. "They will face three bad options: huge tax increases, huge budget deficits or huge and immediate cuts in benefits."

After the speech in Williamsburg this morning, some House Democrats met privately with Bush. Pelosi said Bush defended his Iraq war policy in while acknowledging disapproval of how the war was going so far, the Reuters news service reported.

"The president really stood his ground on Iraq," Pelosi said. She added that Bush "explained why he thought additional troops were needed and why they would succeed this time."