Katie Rogers/The Washington Post

There is not, in other words, all that much you can say with confidence about what Occupy Wall Street is or isn’t. At the moment, it’s different things to different people. And, depending on your perspective, that may be the nascent movement’s biggest strength or its fatal weakness.

Right now, the protests are at a tipping point. The unions and MoveOn.org are mounting a sympathy march this afternoon. Van Jones’s Rebuild the Dream and Russ Feingold’s Progressives United are blasting messages of support. Prominent elected Democrats such as Rep. John Larson, Chairman of the House Democratic Caucus; Rep. Louise Slaughter, ranking member on the House Rules Committee; and Sen. Jeff Merkley have all applauded the movement.

What these Democrats and liberal-activist groups are looking for is something similar to what conservatives found in the tea party: an opportunity to recharge and rebrand. Governance exhausts a movement. The compromises sap it of its purity; the institutional ties rob it of its authenticity; and in times when the American people are unhappy, the consequences undermine its agenda. In 2009, that’s where the Republicans were. The Bush administration had left them identified with an unpopular president, yoked to a terrible economy and discredited as a governing force. So they stopped being Bush Republicans and became Tea Party Republicans.

In 2011, elected Democrats and activist groups affiliated with the Democratic Party are in a similar situation. They’ve compromised on their agenda. They’re yoked to a terrible economy and an unpopular president. They’ve watched the grass-roots energy migrate to the tea party right. They no longer hold the mantle of change. And here, all of a sudden, comes Occupy Wall Street, which seems to have tapped into the zeitgeist, and the slogan “We are the 99 percent,” which is something every liberal message man in town wishes he had come up with. You can see the appeal.

That isn’t to say these groups are trying to co-opt Occupy Wall Street. They’re not. Or, at least, they don't think they are. They just want some of that grass-roots magic, too. They see a space opening up for aggressive, populist organizing, and they want in on it.

That’s not what Occupy Wall Street was founded to offer. Its roots are more radical and anarchist than that. One interesting takeaway from the protest site is that an enormous amount of the energy there is going into sustaining the community at Zucotti Park, which now has to manage food, sanitation, a newspaper (The Occupied Wall Street Journal), marches, a library, a decision-making process, a lost-and-found, and more.

The effort to create “the sort of society you want to have in miniature” makes it hard to turn your attention to changing the society that’s all around you — and that ultimately limits your appeal. The number of people who want to sleep in the park and overthrow the system is not large. The number of people who want to express their frustration with the system and fight for a better deal might be.

The leaderless, decentralized, consensus-driven nature of the protest will make that process of evolution and adaptation easier. After all, there’s no one in particular who can say, “That’s not what this movement is about.” If MoveOn.org begins organizing under the “We Are The 99 Percent” banner, who will stop them?

One very possible future for the movementat it splits in two: The Occupy Wall Street effort, with its more radical aimds and means, continues, and the “We Are the 99 Percent” movement becomes something broader and more directly engaged with the political process. Another is that it fizzles: The radical protest in Zucotti Park peters out, and the effort to create a more mainstream version fails. Another possibility is that it fractures: Just as there are hundreds of distinct tea party groups organized under separate and competing national coalitions, you could imagine a lot of different efforts organized under one name but representing diverse and contradicting ideas.

Ultimately, what’s fascinating about Occupy Wall Street is how big something that small has become. There were hundreds of people in that park, but not thousands. Today’s march might have thousands or tens of thousands of people, but not hundreds of thousands. But it’s growing, and fast. And just as with the tea party, the media are interested in covering it, and the political establishment is interested in joining it. Occupy Wall Street has created a space for some type of populist movement to emerge. What exactly that will look like remains anyone’s guess.

Photos: Seeking 20,000 people to occupy Wall Street