Sens. John Warner, R-Va., and Carl Levin, D-Mich., had been sponsoring competing measures opposing Mr. Bush's strategy of sending 21,500 more U.S. troops to the war zone, with Warner's less harshly worded version attracting more Republican interest. The new resolution would vow to protect funding for troops while keeping Warner's original language expressing the Senate's opposition to the troop buildup.
The resolution could well gain more support from members of both parties than Levin's and Warner's separate versions had been attracting. It lacks Levin's language saying the troop increase is against the national interest, and it drops an earlier provision by Warner suggesting Senate support for some additional troops.
It also is likely to pose a threat to the White House because of its potential appeal to Republicans who have grown tired of the nearly four-year war and want a chance to express their concerns. The White House has been hoping to avoid an overwhelming congressional vote criticizing Bush's handling of the war.
"It's been a hard work in progress," Warner said of his resolution, which has been struggling to win support of 60 senators so as to prevent a filibuster.
The agreement comes as several leading Republicans who support the troop buildup said they will give the administration and the Iraqis about six months to show significant improvement. Many other Republicans say they are deeply skeptical additional troops in Iraq, rather than a political settlement, would help calm the sectarian violence.
The widely unpopular war has led to the deaths of more than 3,000 U.S. troops and is blamed for GOP losses in the Nov. 7 elections that handed control of Congress to the Democrats.
Senate debate on the new resolution, and several proposed by other senators, is likely to begin next week.
The House previously had planned on waiting for the Senate to vote first as a way of testing the waters for Republican support of such a resolution. But according to a Democratic aide, the House will begin the process next week with a committee review. That would set the stage for a House floor debate the week of Feb. 12.
Warner, a prominent Republican and former chairman of the Armed Services Committee, had attracted at least seven other Republicans who were inclined to vote for his resolution. Scrambling to find additional support, Warner added language proposed by Sen. Judd Gregg, R-N.H., that would protect funding for troops.
As of late Wednesday, Gregg had not said whether he would support the revised resolution.
"Colleagues have come up to me and said, 'Can you assure me that this doesn't provide a cutoff of funds?"' Warner said.
It appears the original Iraq resolution, sponsored by Democratic Sen. Joe Biden and endorsed by Republican Chuck Hagel, is losing steam, CBS News correspondent Sharyl Attkisson reports. It expresses symbolic opposition to the president's troop increase.
"It's dead, politically," said one Republican source.