Two powerful liberal groups last week set their sights on more than 40 Republican Members of Congress, launching a series of activities designed to apply political pressure on some of the most burning issues of the day.

Americans Against Escalation in Iraq announced that it was kicking off a project called “Iraq Summer.” Modeled on the “Freedom Summer” of the 1960s civil rights movement, which dispatched organizers to dozens of communities in the South to work for integration, the Iraq program will send almost 100 organizers to the home states and districts of some Republican Senators and House Members who have opposed setting a timeline to end the Iraq War.

Organizers will spend 10 weeks in 40 Congressional districts across 15 states, working with local veterans and advocacy groups to pressure the targeted lawmakers to reject President Bush’s Iraq policy. They will stage a variety of events, including letter-writing campaigns and local rallies.

“Opposition to the war in Iraq has reached a boiling point and this summer Republican members of Congress will be feeling the heat back home,” Moira Mack, a spokeswoman for Americans Against Escalation in Iraq, said in a statement. “The President’s remaining supporters in Congress will be forced to face the political consequences in their districts this summer.”

The targeted Republicans are Illinois Reps. Mark Kirk, Timothy Johnson and Ray LaHood; Maine Sens. Susan Collins and Olympia Snowe; Michigan Reps. Vernon Ehlers, Fred Upton, Tim Walberg, Mike Rogers, Candice Miller and Thaddeus McCotter; Minnesota Sen. Norm Coleman and Reps. Jim Ramstad and Michele Bachmann; New Hampshire Sen. John Sununu; New Jersey Reps. Chris Smith and Mike Ferguson; New York Reps. Jim Walsh and Randy Kuhl; Ohio Sen. George Voinovich and Reps. Steven LaTourette and Deborah Pryce; Pennsylvania Sen. Arlen Specter and Reps. Phil English, Jim Gerlach, Charlie Dent, Tim Murphy and Todd Platts; Virginia Sen. John Warner and Reps. Thelma Drake, Frank Wolf and Tom Davis; Arizona Rep. Rick Renzi; Iowa Sen. Chuck Grassley and Rep. Tom Latham; New Mexico Sen. Pete Domenici and Rep. Heather Wilson; Nevada Reps. Dean Heller and Jon Porter; and Delaware Rep. Mike Castle.

Many face potentially competitive challenges in 2008.

Meanwhile, Defenders of Wildlife Action Fund, whose early attack ads in the 2006 cycle helped soften then-House Resources Chairman Richard Pombo (R-Calif.) for defeat, began airing radio ads Thursday in the districts of Heller, Renzi and GOP Reps. Ken Calvert (Calif.), John Doolittle (Calif.) and Steve Pearce (N.M.), criticizing their stance on global warming. The ads were accompanied by the launch of a new Web site, www.headsinthesand.org, set up to pressure the lawmakers.

Rodger Schlickeisen, president of the environmental group, said in an interview that the ads would air on drive-time radio throughout the five Members’ districts at least through the end of this week.

Although some of the Members could be vulnerable in 2008, Schlickeisen said their political standing was only part of the consideration when it came to placing the ads.

“We started out with the most extreme [on global warming] — the easiest to target,” he said.

Schlickeisen would not say what the organization is paying for the radio ads, but he said others would follow targeting the initial five — with other Members soon to be in the group’s scope.

“I couldn’t even tell you what our full budget is because we haven’t figured it out,” he said.