WASHINGTON—The only pro-war senator to caucus with the Democrats may become a Republican.

That’s what Joseph Lieberman, the independent from Connecticut who was defeated in a Democratic primary last summer, is hinting he will do if his old party fiddles with a bill to pay for the troop surge in Iraq.

Yesterday, Mr. Lieberman told the Web site Politico he had no “desire to switch parties,” but “if that ever happens, it is because I feel the majority of Democrats have gone in a direction that I don’t feel comfortable with.”

That uncomfortable direction, according to the Politico, will concern the $99 billion supplemental military budget request the White House is expected to submit to Congress early next month. While the Senate majority leader, Harry Reid, a Democrat of Nevada, has ruled out any Vietnam-style decision to cut off funding for the war, Republicans are now expecting Democrats in the House to attach conditions to the spending bill, a move they decry as tantamount to micromanaging the war for Iraq.

The political calculations of the Democrats’ 2000 nominee for vice president could potentially tip the balance of power in the Senate. If Mr. Lieberman defected to the Republican caucus, the Senate would be evenly split and Vice President Cheney would cast tie-breaking votes in favor of the Republican side.

Mr. Lieberman’s concerns about his party’s intentions on war funding are in some part motivated by the recent maneuvers of his colleagues in the House of Representatives. Already Rep. John Murtha, a Democrat of Pennsylvania who leads the House’s withdrawal caucus, told the Web site MoveOn.org on February 14 that he would seek to attach an amendment to any funding bill to require that any new troops sent to Iraq for the surge must have been out of the theater for at least a year. That would hamstring the ability of American commanders to call up the GIs they seek for reinforcements in Anbar province and Baghdad.

Yesterday on Fox News Channel, the Senate minority leader, Mitch McConnell, a Republican of Kentucky, predicted that Mr. Murtha’s proposal would “divide Democrats.” As to whether Democrats could succeed, as they did in 1973, in ending funds for the war and reconstruction of Iraq, the minority leader was doubtful. “They could do it if they had the votes and presidential signature,” he said. “I don’t think they have either.”

Mr. Murtha’s threat prompted one of his Republican allies, Rep. Walter Jones of North Carolina, to write Mr. Murtha a public letter urging him to drop conditions on military funding. “As Congress and the President continue to discuss and debate the best way forward in Iraq, no one can debate the need to provide our men and women in uniform with the finest equipment and training available,” the lawmaker, who in 2005 began calling for a withdrawal from Iraq, said. “Anyone who goes into harm’s way under the flag of the United States of America should be deployed with the best our nation can provide.”

Mr. Lieberman, according to a Time magazine story released to the Internet yesterday, has had regular consultations with the White House and Senate Republicans on the war. But yesterday a senior Republican staffer said, “Lieberman hasn’t been given any offers.” This source, who asked to be anonymous, added, “He speaks to the Republican leadership pretty regularly, but there’s no organized campaign to bring him over.”

A spokesman for Senator Reid yesterday that Mr. Lieberman is afforded the same powers as any other Democratic committee chairman.
“Senator Lieberman has no more or less influence than other chairman of a committee,” Jim Manley said. “Senator Lieberman is treated just like any other chairman of a committee. No more, no less,” he said, pointing out that his boss appointed Mr. Lieberman as a floor manager for the upcoming bill on implementing the recommendations of the National Commission on Terrorist Attacks Upon the United States.

“Senator Lieberman votes with the Democratic caucus a majority of the time. There’s just a difference of opinion when it comes to Iraq,” Mr. Manley said.

A spokesman for Mr. Lieberman’s office yesterday said the senator’s comments “spoke for themselves.”

Another Republican senior aide yesterday expressed bewilderment at animosity towards the Connecticut lawmaker from Democratic Party’s base. “Lieberman is a solid Democratic vote for them on everything except, are you willing to fight Al Qaeda?” the staffer said. “On that he votes with us. Just because he raises his hand for that, the base wants to drive him out of the party. Doesn’t that strike you as bizarre?”

For now, the more immediate concern for Republicans and the White House is a new plan from Senate’s chairman of the Armed Services and Foreign Relations Committee to amend the 2002 resolution authorizing force in Iraq. That plan would likely scale back the mission in Iraq to accommodate the phased withdrawal plan favored by the majority of Democrats.