As President Obama sinks in the polls, Democrats and liberal pundits inevitably are searching for a scapegoat. The most likely victim appears to be gaffe-prone Vice President Joe Biden, who has become the focus of speculation that Secretary of State Hillary Clinton just might replace him on the 2012 Democratic ticket. Former Virginia Gov. Doug Wilder, his state's first African-American governor, touched off the controversy. Writing at Politico.com last week, Mr. Wilder argued that Mr. Biden's tenure has been undistinguished and chock full of "too many YouTube moments." He charged that Mr. Biden "has continued to undermine what little confidence...