When the liberal group Campaign for America’s Future kicks off its annual “Take Back America” conference in Washington, D.C., today, Donna Edwards, the nonprofit executive who ousted Rep. Albert Wynn (Md.) in the Democratic primary last month, will play a prominent role.

After trouncing Wynn by almost 25 points, Edwards is a heroine to many liberal activists — living proof, in their minds, that the Democratic Party has been put on notice that incumbents like Wynn who forget to tend to the party’s base can be knocked off in primaries.

“There’s a lot of energy on the part of the activists to go beyond what the party thinks is possible,” said Roger Hickey, co-director of Campaign for America’s Future.

But will that energy translate into real action this election season, and will other Democratic incumbents feel the same kind of pain that Wynn did? Or is the major internecine warfare already over? Have the right and the left already claimed their lone Congressional scalps of the election cycle?

With the defeats of Wynn and Rep. Wayne Gilchrest (R-Md.) in their respective primaries last month, the liberal organizations that helped knock off Wynn and the conservative Club for Growth, which worked feverishly to oust Gilchrest, might be expected to feel emboldened to take on other incumbents who don’t hew to their rigid ideological line.

But while a few House incumbents appear to be vulnerable to primary challengers for a variety of reasons, the ideologically driven groups that knocked off Wynn and Gilchrest don’t seem to have too many other targets in the primaries.

Leaders of both the Club for Growth and some liberal organizations won’t rule out the possibility of aiding additional challengers in primaries this cycle, but they concede that the conditions that prompted them to go after Gilchrest and Wynn don’t exist much elsewhere. Sometimes, they say, the effort it takes to defeat an incumbent in a primary just isn’t worth it.

“An incumbent is never low-hanging fruit unless there’s a scandal,” said David Keating, executive director of the Club for Growth.

On the Democratic side, political insiders at a host of liberal groups said they could see a few House Democrats sweating primary races this cycle, including Reps. Leonard Boswell (Iowa), Jane Harman (Calif.) and Edolphus Towns (N.Y.). Although the trio’s challengers are likely to attract some attention on the liberal blogosphere, it isn’t clear yet whether any of them will work up the momentum and attract the level of support that Edwards did against Wynn.

Boswell is facing a primary challenge from former state Rep. Ed Fallon (D), who has been a thorn in the side of the Hawkeye State Democratic establishment in the past. He won his legislative seat by defeating an entrenched incumbent in a primary, and he infuriated fellow Democrats by endorsing Ralph Nader over Al Gore in the 2000 presidential election.

Fallon unsuccessfully ran for governor in 2006, formed a liberal think tank last year called An Independence Movement for Iowa, and now has set his sights on Boswell, a 74-year-old, six-term incumbent who has been criticized from the left for his 2002 vote in favor of using force in Iraq. But Boswell entered 2008 with $702,000 in his campaign account, while Fallon hadn’t done any fundraising at all.

In California, teacher Marcy Winograd, who heads the Los Angeles chapter of the Progressive Democrats of America, is seeking a rematch with Harman. Criticizing Harman as a hawk won Winograd some attention in 2006, but she still finished 24 points behind the incumbent in the primary and didn’t do any fundraising in 2007. Harman finished the year with just $284,000 on hand, but she is one of the richest Members of Congress and easily can replenish her campaign coffers if she needs to.

In New York, author and community activist Kevin Powell is preparing to challenge Towns in the primary. Towns occasionally runs afoul of Democratic leaders and activist groups, but he was able to hold off two local elected officials in his 2006 primary, taking 47 percent of the vote. Powell, an author and former “Real World” contestant, may be able to create a buzz around his candidacy, but he did not raise a dime in 2007 while Towns banked $227,000.

Meanwhile, Gilchrest hardly is the only Republican Member of Congress who infuriates the Club for Growth, which promotes an anti-tax, pro-economic-growth agenda. But while the group is trying to throw its weight around in several Republican primaries this cycle, they mostly are open-seat races.

With Gilchrest defeated, the one other House GOP incumbent who is feeling the group’s wrath is Rep. Heather Wilson, who is competing with the club’s choice, Rep. Steve Pearce, in the New Mexico Republican Senate primary.

Keating said the circumstances in Maryland’s 1st district this cycle were particularly ripe for attempting to knock off Gilchrest — whom the club also tried to defeat in 2002. For starters, the Congressman was facing a very credible GOP primary challenger in state Sen. Andy Harris, who landed heavy blows by attacking the incumbent’s opposition to the Iraq War and proved to be a formidable fundraiser even before the club weighed in on the race.

“I think we had a great candidate and Gilchrest just had a bad record on economic issues,” Keating said.

The Club for Growth leader conceded that the group might have a bigger incumbent target list if it had a candidate-recruiting operation.

“It might be a nice thing to have some day,” he said.

Even if the Club for Growth isn’t working to defeat other GOP incumbents right now, the Republican Main Street Partnership, a group dedicated to electing and protecting centrist Republicans, is remaining vigilant.

“From my perspective, there will be other candidates who will be looked at by the Club for Growth,” said former Rep. Charles Bass (N.H.), the RMSP president.

Bass, like other Republican critics of the Club for Growth, complained that the conservative group forces the GOP establishment to spend time defending incumbents in primaries instead of going after Democrats. Some Republicans fret that despite the Republican lean of Maryland’s 1st district, Harris may be too conservative for voters there and could find himself in a tougher-than-expected general election race with Queen Anne County State’s Attorney Frank Kratovil (D).

“We are promoting our candidates to win in November, not [just] in the primary,” Bass said. “Club for Growth leaves them as orphans to a weakened [National Republican Congressional Committee] and a difficult political environment.”

But Club for Growth always has been unapologetic for its tactics.

“If somebody’s casting a bad vote in a Republican seat — a bad vote is a bad vote on the floor of the House, whether it’s a Democrat or a Republican,” Keating said.

And even if the ideological groups don’t assemble a huge list of targets, a small number of kills are sufficient to get party leaders to take notice and pay closer attention to the agenda of the activist groups, said Robert Borosage, co-director of Campaign for America’s Future.

“You only have to do one or two each cycle for people to get sobered,” he said.