WASHINGTON -- Amid declining public support for the war in Iraq, two prominent Republican senators urged President Bush yesterday to be more forthcoming about the increasingly costly and uncertain effort to defeat the insurgency and establish a self-sufficient democracy.

"We want to hear from the administration," said Sen. Richard Lugar, R-Ind., chairman of the Foreign Relations Committee. "We want more co-option of the Congress by the administration so that we're on the same wavelength."

Sen. John Warner, R-Va., chairman of the Armed Services Committee, said Mr. Bush should provide a detailed status report to the American public.

"It would bring him closer to the people, dispel some of this concern that understandably our people have about the loss of life and limb, the enormous cost of this war to the American public" and press the case that "we've got to stay firm for the next six months," Mr. Warner said.

The lawmakers made their comments on television talk shows almost two weeks after the Senate overwhelmingly passed a Republican-sponsored resolution calling upon the Bush administration to turn over more control of Iraq to the Iraqis and to provide quarterly reports to Congress on progress toward withdrawing U.S. forces.

Mr. Bush is scheduled to make a speech on Wednesday during which he is expected to tout the readiness of Iraqi troops to assume greater responsibility for the country's security. He will do so as a consensus appears to be emerging in Washington about the need to pull out large numbers of U.S. forces gradually over the next two years.

Democratic senators said the administration's mishandling of the war makes it imperative that it commit to a specific timetable for troop withdrawals or risk leaving behind chaos.

"We have a six-month window here to get it right," said Sen. Joseph Biden of Delaware, the senior Democrat on the Foreign Relations Committee, referring to the way the war was being conducted. "But I have to admit that I think its chances are not a lot better than 50-50, and it requires a real change in course" by Mr. Bush.

Mr. Biden appeared with Mr. Warner on NBC's "Meet the Press."

Sen. Carl Levin, D-Mich., who joined Mr. Lugar on "Fox News Sunday," said if the Iraqis think we're there "as long as we're needed, that is such an open-ended statement on our part that it takes pressure off them to make the compromises that are necessary to make those changes in the [Iraqi] constitution. That's what we need to do: put some pressure on them to make the political decisions that are so essential to becoming a nation."

Sen. Russell Feingold, D-Wis., the first senator to call for a scheduled pullout, said on ABC's "This Week" that "we should have a public timetable to show the Iraqi people, the American people and the world that we're not trying to have a permanent occupation of Iraq."

Mr. Biden and Mr. Feingold said they were considering bids for the 2008 Democratic presidential nomination.