On Monday afternoon, the Transport Workers Union, Local 100, went to court to ask for an injunction to stop the New York Police Department from compelling city bus drivers to transport arrested Occupy Wall Street demonstrators. “We’re a pretty mainstream blue-collar union,” says spokesman Jim Gannon. “We view the protests as young people who are articulating the same kind of things that we’ve been trying to articulate.”

Gannon’s union was one of the first to throw its support behind the demonstrators, and members will be marching with them in a protest Wednesday afternoon. He sees, in the anarchic Wall Street encampment, a sign of a grassroots revolt against austerity economics. “They’ve really thrown a spotlight on issues that are bothering people, especially bothering workers like our members,” he says. “Right now, we’re discussing how we’re going to give them material support, what we should do for them.”

A couple of weeks ago, Occupy Wall Street seemed destined for marginality. In July, when the Canadian anti-corporate organization AdBusters put out the call for demonstrators to camp out in the heart of American finance, it envisioned 90,000 participants, but only about a thousand showed up. For the first week, there was hardly any mainstream media coverage at all. But now, helped in part by publicity from police brutality and mass arrests, the demonstrations are mushrooming, capturing the attention of people all over the country. More and more people are turning up in New York’s Zuccotti Park, while similar protests are breaking out in dozens of cities nationwide. Suddenly, mainstream progressives are wondering if this could be the beginning of the left-wing populist uprising they’ve been waiting for.

“It’s so thrilling,” says Van Jones. The former Obama adviser is a founder of the American Dream Movement, whose inaugural conference kicked off Monday in Washington, D.C., with a live feed from the demonstrations. The protesters, he says, “are calling the conscience of America back to this economic catastrophe. Nobody has been able to do that.”

On Wednesday, several unions, including TWU, the United Federation of Teachers, and the Service Employees International Union, will be participating in an Occupy Wall Street march. MoveOn.org sent out its first email blast about the protests on Sunday. “We have been focused for much of the summer and fall on the need to make Wall Street and corporations pay their fair share,” says Justin Ruben, MoveOn’s executive director. “When this sprung up, we were watching with interest. As it grew last week, and as similar protests started springing up around the country, we thought it was important to bring it to our members’ attention and to make it clear that the concerns these folks are raising are broadly shared, certainly by our members and I think by the majority of the American people.”

It remains an open question whether the Occupy Wall Street movement can attain the same sort of national resonance as the Tea Party. Both are subcultures, but only Occupy Wall Street presents itself that way. The movement is steeped in the rhetoric, aesthetics, and folkways of an international, anarchist-inflected protest movement that can be alienating to people on the outside. Describing Occupy Wall Street’s decision-making body, the General Assembly, Nathan Schneider writes, “Get ready for jargon: the General Assembly is a horizontal, autonomous, leaderless, modified-consensus-based system with roots in anarchist thought.” Few people who aren’t already committed to the movement are likely to have patience for this sort of thing. Meanwhile, drum circles and clusters of earnest incense-burning meditators ensure that stereotypes about the hippie left remain alive.

Some Occupiers are so alienated from politics of any sort that they see their encampment as its own goal. “We’re creating our own self-sustaining community here,” says Jeff M., a 25-year-old musician who declined to provide his last name. As he spoke, he unpacked boxes of donated clothes, underwear, and blankets sent from all over the country, all of which are being handed out for free. “We’re showing other people that ‘Listen, we don’t need to rely on big corporations. We can work together.’ I know there are a lot of people here who are working on setting up classes on how to provide your own shelter, to sew your own clothes.” Whatever the value of this sort of freegan survivalism, its appeal is probably limited.

But it’s really easy to overstate this side of Occupy Wall Street. Some of what’s going on is utopian and self-indulgent, but many of the protesters have clear-cut political agendas and serious demands. One sign on Monday read:NO MORECARRIED INTEREST LOOPHOLESTAX BREAKS FOR BONUSES & STOCK OPTIONSCEO PAY INFLATIONBRING BACK GLASS STEALGAL!

It doesn’t get much more concrete than that.

Thus unions have recognized that despite some stylistic differences, Occupy Wall Street shares many of their goals. For progressives, this alliance is a tremendously encouraging sign. After all, one of the iconic moments from the 1970s was a bloody brawl on Wall Street between hippies and construction workers; as Rick Perlstein wrote in Nixonland: “Workers singled out for beating boys with the longest hair. The weapons of choice were their orange and yellow hard hats.” This time around, there’s visible solidarity between blue-collar workers and the counterculture.

“This really started in Wisconsin,” with the protests against Gov. Scott Walker’s attacks on unions there, says Gannon of the nascent movement. “I’m old enough to remember the Vietnam antiwar movement. It definitely feels like that. Young kids, college kids, who see something they don’t like—they’re stepping up.”