Like the Tea Party movement, Occupy began as a leaderless, grass roots effort. But over time the Tea Party adopted a group of national leaders as the face of the movement, a decision that helped it convert public energy into tangible political gains during the 2010 midterm elections. Some now wonder whether the Occupy movement needs to take a similar turn, and Warren stands out among the movement’s potential leaders, a fact that has made her ambivalent stance toward the movement all the more poignant.

“I think change is possible from within the system,” Shafer said, “We see that with Tea Party candidates.”

—Staff writer Caroline M. McKay can be reached at carolinemckay@college.harvard.edu.

This article has been revised to reflect the following correction.

CORRECTION: Dec. 17, 2011.

Due to an editing error, an earlier version of the Dec. 16 article “Political Ads Highlight Warren's Ambivalent Relationship with Occupy” misstated the name of the political action committee that ran an ad attacking Senate candidate Elizabeth Warren. The ad was funded by Crossroads Grassroots Political Strategies, not American Crossroads.