WASHINGTON - Tens of thousands of demonstrators are set to arrive in the capital this weekend for a major antiwar march, staging the first of several protests intended to persuade the new Democratic-controlled Congress to do more than simply speak against President Bush's Iraq policy.

Do not look for senators to be standing among the protesters on the Mall tomorrow. Despite a consensus building around a Senate resolution to oppose sending more troops to Iraq, even the most liberal Democratic senators do not appear eager to align themselves with a traditional antiwar protest.

So the groups organizing the demonstrations against the president's strategy are also carrying out a sophisticated, well-financed lobbying campaign on Capitol Hill. Their behind-the-scenes efforts are intensifying, relying on tactics usually deployed in a cutthroat political race.

Americans Against Escalation in Iraq, a coalition of labor unions, Moveon.org and other groups that have traditionally rallied against wars, has raised $1.5 million since it was formed two weeks ago. The group is singling out Republicans and Democrats who have spoken out against the war, but who have so far declined to pledge support for a resolution denouncing the plan to increase the number of troops.

Next week, the group intends to fly Iraq veterans to the home states of Republican senators who serve on the Foreign Relations Committee and voted on Wednesday against the resolution condemning the administration plan, including Sens. Norm Coleman of Minnesota and John E. Sununu of New Hampshire. Television advertisements are scheduled to be shown in some of the same states in an effort to apply pressure before the Senate vote on the resolution in early February.

"The face of antiwar is not what it was in the '70s," said Jon Soltz, a veteran of Iraq and Afghanistan who is chairman of a group called VoteVets.

If members of Congress are slowly finding their voice opposing the administration's Iraq plan, aides to lawmakers say, it is in no small part because of the face-to-face lobbying campaign that is a central piece of the strategy employed by Americans Against Escalation in Iraq. The group plans to spend up to $9 million, said its spokesman, Brad Woodhouse, which they expect to raise through Internet solicitations and individual donations.

Soltz and nearly a dozen other veterans have been walking the halls of Congress, and they have had no problems getting appointments. One day last week, they held back-to-back meetings with Sens. Hillary Rodham Clinton and Barack Obama, both of whom are running for president in 2008.

"This battle to oppose the escalation is as important as the original battle in Iraq," said Jonathan Powers, who served 14 months in Iraq as a captain with the 1st Armored Division. He laced up his combat boots and put on a blue suit as he went to Congress on a recent day of lobbying.

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Senate leaders said Thursday that it appeared unlikely that any vote on an Iraq resolution would occur until the week of Feb. 5. Efforts to meld differing resolutions opposing the troop buildup faltered Thursday when Sens. John W. Warner, Republican of Virginia, and Ben Nelson, Democrat of Nebraska, chose not to negotiate with those behind a competing plan approved by the Foreign Relations Committee.

Sen. Joseph R. Biden Jr., the Delaware Democrat who is the chairman of the panel, and his allies had offered to try to merge the resolutions, saying the differences could be overcome, clearing the way for a consensus measure.

But Warner has been reluctant to consider the idea of merging the two, a move that could bring a strong bipartisan vote against the president. In a written response to Biden, Warner and Nelson said they would rather work out any disagreements on the floor "as a consequence of the will of the Senate."

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In an interview on Thursday evening, Biden expressed disappointment that Warner did not agree to negotiate, but he added that a full-fledged debate on the Senate floor would be "healthy."

Coleman said he saw the Warner approach as less partisan than the plan offered by Biden and allies who included Sen. Chuck Hagel, Republican of Nebraska.

"The Warner resolution, I think, offers an opportunity for a lot of us to express a concern about an aspect of the policy without taking a shot at the president," Coleman said.

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At the White House, the spokesman Tony Snow acknowledged the administration had been talking with Warner about his initiative. "We're trying to take his temperature on what he intends," Snow said.

Supporters of the president's policy were developing resolutions of their own. Sen. John McCain, Republican of Arizona, said he would propose giving the Iraqis a series of benchmarks to demonstrate progress. A draft proposal from Sen.