But by April 2007, when he was running for president, Richardson said he would leave no residual forces in the country. In fact, he's stated that position over and over in debates and on his web site as a way to distinguish himself from the Democratic frontrunners. So we'll take him at his word that he's opposed to residual forces.
But what is Richardson's definition of a residual force? Biden's attack cites a Richardson interview with George Stephanoupoulous on April 15, 2007. In that interview, Richardson said, "I would station some in the region. I would put a majority of them in Afghanistan, where al Qaeda and the Taliban are really, right now, resurrecting. But I would not put them in Iraq. I believe I would leave Marine forces to protect our embassy and other vital American installations. But the point here is, leaving a residual force is going to invite more violence and make our troops targets."
Based on that statement, it seems Richardson doesn't consider Marines guarding an embassy to constitute a residual force. But Richardson's web site www.getourtroopsout.com states that Richardson would leave "zero" troops in Iraq. His campaign didn't respond to a question on the embassy issue.
Based on the 2006 Hardball interview, though, Richardson seems to have genuinely changed position on residual forces. And that's the charge that Biden is making.