Advocates of “clean coal,” hopeful of pushing their cause at Obama-Biden campaign events, say that organizers have confiscated T-shirts, hats and signs and harassed supporters.

At a Chesterfield, Virginia rally Tuesday for Vice President Biden, clean coal supporters said that their T-shirts, hats and signs were taken as they passed through security. Others said that they were barred from entering after an official who had earlier confiscated clean coal T-shirts called it a “private event.”