As the Occupy Wall Street demonstrators moved to Washington on Thursday and swarmed outside the U.S. Chamber of Commerce, President Obama was at the other end of Lafayette Square trying to align himself with the swelling protest movement.

“I think it expresses the frustrations that the American people feel, that we had the biggest financial crisis since the Great Depression, huge collateral damage all throughout the country, all across Main Street, and yet you’re still seeing some of the same folks who acted irresponsibly trying to fight efforts to crack down on abusive practices that got us into this problem in the first place,” the president said at a news conference in the East Room.

For the struggling president, the nascent movement offers a chance at salvation, the opportunity to excite liberals with the sort of populist energy that has fueled the Tea Party for two years. But, as liberal leaders already know, the young movement must be careful to avoid Obama’s embrace: He decimated the progressive cause once, and he would do it again if given the chance.

Liberal activists who rallied behind Obama in 2008 watched as he defied their wishes and instead made unrequited concessions to the Republicans. “Every one in this crowd, I am certain, has had disappointments and frustrations with this White House,” Robert Borosage, a director of the Campaign for America’s Future, told the audience as he convened the Take Back the American Dream Conference, an annual gathering of liberal activists in Washington, this week. He accused Obama of being “too cautious” and “pre-compromised” and criticized his performance on jobs, global warming, defense and foreign policy.

Another of the speakers at the confab, former Obama White House official Van Jones, said it was liberals’ own fault for placing too much faith in the president. “We all affiliated [with] him,” he said. “We made a mistake.” Obama “got to become head of state, he got promoted — good for him,” said Jones, who was forced to quit the White House when conservative critics attacked him. “But here we are — and it’s worse than before.”

But the most striking thing about the progressives’ gathering this week was how little Obama was mentioned, and how dismissive the few mentions were. When one woman at the convention attempted to ignite Obama’s trademark “fired up!” cheer, only a few people responded with the usual answer, “ready to go!” The attempt quickly died.

Rep. Donna Edwards (D-Md.) came closer than most in defending Obama, with a less-than-ringing endorsement. “I haven’t always been the happy Democratic camper, okay?” But, in terms of liberals’ goals, “we can get there faster with our crowd than we can get there with their crowd.”

The more successful appeals ignored Obama in favor of calls to turn the Wall Street protests into a “movement moment” to target corporate greed and, as one protest flier put it, “Wall Street’s servants on K Street, in the Pentagon and in our government.”

That would seem to be a fat and juicy target. American companies are sitting on $2 trillion in cash while nearly 15 million of their countrymen are out of work. And Washington does nothing, in large part because vast swaths of the town are controlled by corporations. Some 5,400 congressional staffers have joined lobbying outfits in the last decade, according to a LegiStorm study, and 605 current congressional staffers have lobbied in the last decade. The Center for Responsive Politics counts 328 Obama officials who have already passed through the revolving door to corporate riches. Of the 120 lawmakers who departed from Congress last year, 39 are now in the lobbying trade.

The Democrats, however, have been unable — or unwilling — to turn the corporate excess to their political benefit. The Democratic National Committee’s latest attempt, a Web ad released Wednesday, shows various Republican presidential candidates calling for repeal of the Dodd-Frank financial reforms, a piece of legislation the average voter almost certainly doesn’t know about.

Then there’s Obama, entirely too even-handed to be a populist. “I think people are frustrated, and the protestors are giving voice to a more broad-based frustration about how our financial system works,” he said during Thursday’s news conference. But in the next breath, he added: “Now, keep in mind I have said before and I will continue to repeat, we have to have a strong, effective financial sector in order for us to grow.”

True, but uninspiring. And liberals should by now know that a nuanced president cannot be a movement’s mouthpiece.