The six days of protests against Walker’s bill to curb collective bargaining rights have mesmerized cable news viewers and shown a fighting spirit and cohesion that labor groups have rarely displayed during 12 months of serving as public enemy number one in the eyes of tea party insurgents and newly empowered budget cutters.

Yet that sense of determined harmony comes at a potentially steep cost, and with no clear endgame. Some strategists and labor officials watching the protest conflagration from the outside are beginning to fret that a large-scale defeat in Wisconsin will have a devastating ripple effect, weakening labor state by state throughout the rest of the country.

“Some of the labor people are saying, ‘It’s the beginning of the fight back,’” said a top labor official. “But if the labor movement rallies and gets run over in Wisconsin, it opens [the gates] in every state” for governors to start pushing harder to curtail labor rights.

“Not every state’s going to roll back collective bargaining,” the official — who, like many, asked not to be named to avoid undermining the protests — added, but said it could open the gates for union losses on various fronts, like benefits.

Even as union officials hailed solidarity rallies, White House support and sympathetic pizza orders from all over the nation for protesters, the difficult politics on the ground began to take their toll Sunday. Wisconsin teachers — whose walkouts last week forced school closures in many districts — were urged back to work by their union leaders. At the same time, Republican state officials said they wouldn’t wait any longer for Democrats who fled the state to stall legislation.

“Tomorrow they begin again in their schools and classrooms,” Wisconsin Education Association Council President Mary Bell said in a statement. “Their voices will remain strong, and they will continue to be heard wherever and whenever they can.”

She urged people to “return to duty by day and find ways to be vocal and visible after their workday is done. … We send this message to Wisconsin’s educators and parents as a show of good faith.”

Yet “good faith” offerings seemed almost quaint to some inside the labor movement who said the protests’ organic nature is as much a result of poor planning as a reflection of from-the-heart support. The public backing from President Barack Obama, meanwhile, was a cost-free love letter to his union backers — and the Democratic National Committee quickly distanced itself Friday from reports that it was masterminding protests.

“Whatever happened to the vague sense 10 years ago of the need to develop a community unionism?” asked another official, who suggested labor leaders on the ground in Wisconsin shouldn’t have been surprised by the Walker attack, yet were clearly caught off guard. “They’ve been talking only to themselves for too long.”

Many strategists and even some labor officials argue that the genuine passion and emotion being felt and displayed on the ground in Wisconsin is obscuring a central problem: Unions still haven’t figured out even a semblance of an effective PR strategy.

That includes, in many places, not taking steps that could help them, such as trying “to dress up something that looks like a sacrifice and say, ‘Here’s what we’re doing,’” another labor leader lamented.

To be sure, as many labor officials quickly point out, the fight in Wisconsin and in a handful of other states is on a scale that requires a new strategic playbook — it goes much further than fights over pensions and benefits, which have been the hallmark of most union-versus-government battles in states like New Jersey, California, Indiana and Minnesota.

“Labor could not have walked away from this,” said Norman Adler, a longtime lobbyist for public sector labor unions in New York. “Whether there are risks or not … if they lose, they just have to reconfigure their tactics and move on.”

He added, “Whatever happens in Wisconsin, this is going to be replicated elsewhere. The unions can’t back off of this — it would be like hiking up a white flag. And that’s why a lot of private-sector labor [is backing the efforts]. Nobody can risk losing true collective bargaining.”

Ken Sunshine, a Democratic strategist with ties to labor unions, agreed.

“You’ve got to put your stake in the ground somewhere, and the governor there was so outrageous about ending collective bargaining,” Sunshine said. “For labor’s future, they have to pick a good fight, and this one has obviously become it.”

But this fight isn’t at the time or place of the unions’ choosing. Hostility to public-sector workers, including teachers, is at an all-time high amid a recession and a new national mania for curbing the tide of fiscal red ink. Walker appears to have a firm legislative majority on his side.

And labor is struggling to explain — and convince a voting public that has inched away from the concept of unions as a bedrock American institution over the years — that while it’s willing to be flexible on Walker’s demands for cost control, his attempts to change the rules governing public unions are a matter of institutional life and death and union principle. Labor hopes the public will see Walker’s attempt to use a budget gap to reshape labor-management relations as an overreach. But for many people watching from afar, the details of what Walker wants to accomplish have gotten lost, and the fight is playing out as yet another in a long string of recent state-based brawls over the high cost of the public sector.

Bradley Tusk, a former Illinois deputy governor and New York Mayor Mike Bloomberg’s 2009 campaign manager, said that if Walker succeeds in the fight, “this will be portrayed as a major change toward fiscal sanity and protecting taxpayers.”

“The average voter will never feel any pain from it,” he added, “so the high ground shifts away from labor. That puts Obama and other Democrats in the position of being forced further to the left, or moving more toward the GOP position and risking losing support from labor. … This almost creates some of the problems that a primary forces on the challenger.”

As a broader issue, in other states, national union officials think they’ve found a winning strategy in shifting the fight off government and slamming Wall Street, armed with repeated polls that show anti-financial industry sentiment at an all-time high.

Yet so far, it hasn’t been enough to counter the perception that labor is taking from a public trough — and some labor officials believe it’s because unions are retrenching after failing to creatively crafting a message for a new era.

That defensive posture, another labor official argued, has been, “‘I earned that pension,’ or ‘We do good work.’” With the prolonged recession, that stance is no longer enough, the official said.

“Nobody is saying, ‘We hear what’s going on, and here’s what we’re doing,’” the official said.

Adler argued that the PR fight is too little, too late.

“Labor pretty much lost the PR fight a number of years ago,” he said, suggesting the true targets of opportunity at the moment are state lawmakers who are “on the fence,” and can be swayed because they’re worried about getting elected back home. “And I think their position is that they have to show political muscle here.”