Having handed President Bush another $100 billion for the Iraq War with no strings attached, Congress has set itself up for a long, hot summer of discontent.

Seething anti-war groups already are launching ad campaigns and warning of retribution for Members of both parties who voted for the war. And while Republican leaders celebrated their legislative victory on Capitol Hill last week, nervous GOP lawmakers fearing another electoral bloodletting have made it clear that the administration has to show results soon.

Although the next binding decision point on whether to continue the war will come in September, when Gen. David Petraeus will report to Congress and the next war supplemental comes to the floor, House Democrats in the meantime plan to have a series of war votes designed to ratchet up the pressure on Republicans. At the same time, a bipartisan group of Senators is pushing legislation calling for the implementation of the Iraq Study Group recommendations.

“This summer will be very important here in Washington as Republicans will be consistently asked to take a vote on bringing an end to the current course in Iraq and bringing a new direction,” said House Democratic Caucus Chairman Rahm Emanuel (Ill.). “The ultimate goal here is to make sure the Republicans understand the American people … want a new direction to our Iraq policy that focuses on fighting terrorism and not policing a thousand-year civil war between Shia and Sunnis.”

Anti-war groups also vow a long summer campaign. Americans Against Escalation in Iraq launched a new ad campaign targeting GOP Sens. Susan Collins (Maine) and Norm Coleman (Minn.) and vowed to keep the pressure on members of both parties.

“AAEI is turning up the heat on all Members of Congress who continue to support the war — irrespective of party — to make it so hot that they are forced to abandon Bush’s war once and for all,” said spokeswoman Moira Mack.

MoveOn.org urged its followers to send “weak tea” bags to Senate Majority Leader Harry Reid (D-Nev.) for embracing the bill he had earlier criticized.

And Eli Pariser, executive director of MoveOn.org Political Action, pledged retribution regardless of party for backers of the bill. “Our members will be working to hold them accountable through organizing on the ground, advertisements on TV and every other mechanism we have in the months ahead,” he said. “This will be the last Iraq bill that President Bush signs without timelines or teeth.”

While Democratic leaders and rank-and-file Members fractured over whether to fund the war without a timeline for withdrawal, they sought to paper over that split for now by pointing the finger at Republicans.

“There are really only two groups of people standing in the way of change in Iraq,” said Rep. Chris Van Hollen (Md.), chairman of the Democratic Congressional Campaign Committee. “One is President Bush and the White House, and the other are Republican Members of Congress who continue to be a rubber stamp for the White House.”

House Majority Leader Steny Hoyer (D-Md.), who voted for the war bill, also sought to paper over the split. “There are 232 Democrats that believe that our policies in Iraq are failing,” he said. “There are 232 Democrats in the House of Representatives that … believe we need to move in a new direction. … The American public should know that the Democratic Party is united.”

Republicans, meanwhile, sought to make it clear that they are not prepared to indefinitely stay the course.

“I think that the handwriting is on the wall that we are going in a different direction in the fall, and I expect the president to lead it,” said Senate Minority Leader Mitch McConnell (R-Ky.). “He himself has certainly indicated he’s not happy with where we are.”

McConnell acknowledged the political pressure on Republicans, calling it “a statement of the obvious that the Iraq War is not popular and it’s a statement of the obvious that that’s the reason you’re looking at the Republican leader and not the Majority Leader.”

Other Republicans say September may be too late to see changes in Iraq, with Sen. John Warner (Va.), the author of the benchmark language, urging Bush to change course by July if the situation continues to deteriorate. Other Republican Senators also are talking more urgently of their desire to draw down the number of troops in Iraq, even as they opposed any timeline for starting to bring them home.

“It really is critical that we move towards consensus as a people, as a government, as we address the issue of how we’re going to draw down troops in Iraq and make sure that in that drawdown we maintain stability of the government and also the security of our nation,” Sen. Judd Gregg (R-N.H.) said.

A bipartisan group of Senators including Gregg also is working on legislation that would implement the recommendations of the Iraq Study Group, which called for, among other things, transitioning U.S. combat forces into a support role by some time in 2008.

After the deal was reached on the war funding, Bush appeared to try to reduce any expectations for a sudden turnaround, acknowledging last week that violence may very well spike this summer in advance of Petraeus’ report and saying it will be difficult for the Iraqis to make the political progress included as benchmarks in the war supplemental.

Bush added that his goal eventually was to follow the Iraq Study Group outline of transferring U.S. troops to a support role and going after al-Qaida. But Bush said he determined that the surge was needed to stabilize the capital first.

“The decisions I made are all aimed at getting us to a different position, and the timing of which will be decided by the commanders on the ground, not politicians here in Washington,” Bush said.