The majority of Americans are now backing President Barack Obama’s Afghanistan war plan, according to a new poll that comes amid growing House GOP support for a strategy with a flexible timeline.

A Quinnipiac poll released Monday found that 57 percent of Americans say fighting the war is the right thing to do, compared with 35 percent who oppose the effort. The findings reflect a 9-point jump in public support in the last three weeks.

Armed Services ranking member Howard McKeon (R-Calif.) said that trend reflects a sentiment among Republicans, who are feeling better about Obama’s plan now that the administration has signaled more flexibility with its July 2011 timeline for troop withdrawals.

The withdrawal date “has been sufficiently muted,— said McKeon. He pointed to recent comments by Defense Secretary Robert Gates clarifying that the plan to start bringing troops home in July 2011 is shaped by conditions on the ground.

McKeon said Republicans have also had their concerns eased after hearing committee testimony from Gen. Stanley McChrystal, the top field commander in Afghanistan, and Karl Eikenberry, the ambassador to Afghanistan. Both appeared before the House and Senate Armed Services committees Tuesday.

Rep. Kay Granger (R-Texas), who serves on the Appropriations Subcommittee on Defense and just returned from a trip to Afghanistan, similarly predicted more GOP support for the war plan now that administration officials are clarifying a looser timeline.

Obama said in his address last week that troops would come home in three years, but the administration is now saying that July 2011 is when withdrawals “can begin at some number. That’s very different than saying we’re going to take our troops out,— said Granger.

Democrats, eager to support the president but wary of prolonging the war, continue to struggle with how to proceed. Liberals remain opposed to troop increases while fiscal conservatives are weary of adding hundreds of billions more to the already exploding deficit.

House Majority Leader Steny Hoyer (D-Md.) speculated Tuesday that lawmakers ultimately would follow the lead of public opinion, even though many are unsure of where they stand right now.

“I think, generally speaking, the Congress reflects the public’s attitude,— said Hoyer. For now, though, “I think you have a lot of members who are very, very reticent about whether success is possible in Afghanistan.—

Rep. Chris Van Hollen (D-Md.), who is Assistant to the Speaker and chairman of the Democratic Congressional Campaign Committee, said he, like many Democrats, is still on the fence on Obama’s strategy.

“We’ve had a lot of discussions, but we’ve never had any kind of vote on this question,— said Van Hollen. “People are in the listening mode and they’ll certainly be listening to their constituents as part of that. I’m currently in the listening mode.—

Lawmakers will have their chance to vote on Obama’s war plan later this month, when the fiscal 2010 Defense spending bill comes to the floor. Funds in that bill will go toward supporting troop increases and military operations in Afghanistan into the spring, at which point Obama will need more funding approved by Congress.