WASHINGTON (AP) – Two senators leading separate efforts to put Congress on record against President Bush’s troop buildup in Iraq joined forces Wednesday, agreeing on a nonbinding resolution that would criticize the plan.

Senator Warner, Republican of Virginia, and Senator Levin, Democrat of Michigan, had been sponsoring competing measures opposing Mr. Bush’s strategy of sending 21,500 more American troops to the war zone, with Mr. Warner’s less harshly worded version attracting more Republican interest. The new resolution would vow to protect funding for troops while keeping Mr. 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 Mr. Levin’s and Mr. Warner’s separate versions had been attracting. It lacks Mr. Levin’s language saying the troop increase is against the national interest, and it drops an earlier provision by Mr. Warner suggesting Senate support for some additional troops.

“It’s been a hard work in progress,” Mr. 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 American troops and is blamed for GOP losses in the Nov. 7 elections.