PROVIDENCE, R.I. >> Web-savvy members of the political left have found the root of their problem — the super PACs unleashed by the Supreme Court’s Citizens United ruling. They just do not know how to solve it.

This year’s Netroots Nation conference fell just days after Tuesday’s failed effort to recall a union-busting Republican governor in Wisconsin. The liberal activists and bloggers who gathered at the four-day conference here were clearly upset that their highly refined ground game could not overcome the huge financial advantage held by the governor, Scott Walker, and his forces.

Walker’s victory was attributable only in part to the Supreme Court case that paved the way for unlimited donations to outside political groups. Still, the conference attendees feared that, especially in down-ballot races, super PACs would cause their candidates to be hit with a barrage of attack ads that they cannot match.

“The reality is we’re not going to change the system overnight,” said Daniel Mintz, campaign director at MoveOn.org. “This is a new world, and if we don’t figure it out, we’re going to have a lot more losses than wins.”

Others suggested voters would get weary and cynical of the barrage of ads.

“In the long run, people are going to stop believing the ads,” said Alan Grayson, a popular figure among the Netroots. A firebrand former congressman from Florida, Grayson lost his seat in 2010 but is running again in a more favorably drawn district. “Everybody’s campaign is going to be different because of the effect of Citizens United,” he added.

SUCCESS, INTERRUPTED

By some measures, the left had a successful year. There was Occupy Wall Street and the defeat of anti-union legislation in Ohio. Social media campaigns restored financing to Planned Parenthood from the Susan G. Komen Foundation and eliminated much corporate money going to the American Legislative Exchange Council, a conservative organization behind policies like the Stand Your Ground law at the center of the Trayvon Martin case in Florida.

And an apparently improving economy combined with a toxic Republican primary eased worries about President Barack Obama’s re-election. But that has changed in the last few weeks.

“I fear Mitt Romney, I fear a Republican Senate and I fear a Republican House,” said Paul Baker, 62, who co-founded a Chicago-based company that builds apps to promote government transparency.

Last year’s conference was marked by the left’s frustration with the president, but this year, his name simply did not come up much — and when it did, it was invariably paired with a favorable comparison to Romney. As Van Jones, a former Obama administration official, said, they are “no longer comparing Obama to the almighty and instead are comparing him to the alternative.”

The president addressed the Netroots via a video stressing promises he kept and featuring a family that relies on the health care overhaul to pay for their son’s hemophilia medication. But his campaign did not send a senior aide or surrogate. An Obama-Biden booth in the exhibition hall attracted a steady stream of people signing up to volunteer or discuss blogging about the election, and his digital outreach team hosted nuts-and-bolts sessions about online training and using Microsoft Excel.

THE LEFT’S NEW STAR

Elizabeth Warren, on the other hand, received standing ovations both before and after her speech on Friday. Though she is running for Senate in Massachusetts, Warren, a consumer watchdog and Harvard Law professor, has become a national star of the left.

“The Republican nominee said corporations are people,” Warren said. “No, Mitt, corporations are not people. People have hearts, they have kids, they get jobs, they get sick, they love, cry, they dance, they live and they die. Learn the difference.”

Just hours later, at a party hosted by the AFL-CIO, attendees were bemoaning the influence of big money in politics, but were at a loss of what to do about it, barring changing campaign finance laws. Many were resigned to ceding the ad war to the right.

Strategists are considering ways to “inoculate” candidates against negative advertising through an improved ground game, and an emphasis on using social media for personal interaction and persuasion, rather than blasting messages indiscriminately. Some expressed a heightened sense of urgency behind oft-discussed aspirations of financing a liberal message machine, from bloggers to radio stations.

“Donors are getting increasingly frustrated with funding TV ads, which might win an election but don’t create lasting value,” said Kari Chisholm, an Internet campaign strategist from Portland, Ore.

While Netroots Nation is perhaps the most prominent gathering of left-wing critics of the Democratic establishment, they were nonetheless reminded of the left’s fractious nature. Across the street, Occupy Wall Street protesters camped out, calling for taxes on the wealthiest 1 percent and drawing attention to a state bailout of 38 Studios, the video game company of the retired baseball star Curt Schilling.