The Green Party presidential candidates debated each other in San Francisco on Sunday afternoon, January 13. The event attracted a paying audience of about 800 people. The presidential candidates were Jared Ball, Jesse Johnson, Cynthia McKinney, Kent Mesplay, and Cat Swift. Ball announced at the end of his closing statement that he would be devoting his energy toward helping Cynthia McKinney obtain the nomination, so one could say that at that point, he withdrew as a presidential candidate.
After the debate was over, Ralph Nader spoke briefly, and also took questions from the audience. He did not talk about the presidential election, and gave no indication that he will be declaring his candidacy for the Green Party nomination.
Here is the San Francisco Chronicle story about the event.