WASHINGTON – Sen. John Warner, an influential Republican on military affairs, introduced a bipartisan resolution Monday that opposes President Bush’s plan to send 21,500 more American troops to Iraq and urges shifting U.S. soldiers out of the middle of the sectarian killings that are raging in Baghdad.

Sen. Susan Collins, R-Maine, who helped draft the resolution, joined Warner in presenting the measure, which, on the eve of Bush’s State of the Union address, was one of two strong signals that Republicans in Congress sent Monday showing their doubts about the war. The other came from Republicans in the House of Representatives, who said they wanted Bush to certify monthly whatever progress was being made in Iraq on military, political and social benchmarks.

Combined with near-unanimous Democratic opposition to Bush’s war policy, the Republican stands show a broad bipartisan lack of confidence in the president’s course.

Warner said the United States already had “made a tremendous sacrifice in our nation of life and limb and largess” to establish Iraq’s sovereignty, and that now Iraqi forces should stop the violence.

Under the president’s plan, U.S. troops would be asked to help stop the death squads and bombings now racking Baghdad.

“I feel ever so strongly that the American GI was not trained, not sent over there, certainly not by resolution of this institution, to be placed in the middle of a fight between the Sunni and the Shi’a and the wanton and just incomprehensible killing that’s going on at this time,” Warner said.

House Minority Leader John Boehner, R-Ohio, who supports Bush’s troop increase, made the recommendation for a monthly benchmark report in a letter to House Speaker Nancy Pelosi, D-Calif., and proposed that Pelosi create a bipartisan select committee to oversee the reports.

“Congress cannot and must not dictate the strategies or methods used in war,” Boehner’s letter said, “but we have a duty to the American people to candidly and honestly assess whether our efforts have been successful.”

While Warner’s resolution could pull support from a more strongly worded resolution of no confidence in Bush’s Iraq policy that Democratic Senate leaders are promoting, it also could be the starting point for negotiations toward a compromise resolution opposing the troop increase that would win broad bipartisan support.

The resolution drafted by Warner, Collins, and Ben Nelson, D-Neb., and supported by Sen. Norm Coleman, R-Minn., is nonconfrontational in tone. It stresses that the Senate doesn’t question the president’s power as commander in chief and notes that Bush himself, when he announced his new plan Jan. 10, invited members of Congress to suggest ways to improve it.

It’s similar in key ways to a resolution proposed last week by Sens. Joseph Biden, D-Del., Carl Levin, D-Mich., Chuck Hagel, R-Neb., and Olympia Snowe, R-Maine, and favored by Senate Democratic leaders.

Both resolutions oppose Bush’s plan to increase the number of American troops in Iraq. Both stress that the job of quelling the fighting in Baghdad should belong to the Iraqi government, while U.S. troops should help protect Iraq’s territory from outside assault, fight terrorists and train Iraqi troops.

But Warner’s and Collins’ resolution avoids one politically loaded term: escalation. It uses the word “augment” to describe the president’s increase in forces; the Biden resolution calls it “escalating” the U.S. military presence.

Warner said he’d vote against Biden’s resolution as drafted but that he might support it if it were revised. The task of polishing the wording now goes to the Senate Foreign Relations Committee, which Biden chairs.