"I Endorse David Vitter For Governor" was the subject line on an email from Kentucky U.S. Sen. Rand Paul last week. Paul and Vitter have worked together on legislation before, including a 2011 bill that would have ended "birthright citizenship" and established a law making babies born on American soil U.S. citizens only if their parents were here legally. The email came with a donation link to the Vitter campaign. Within hours, the Louisiana Democratic Party had fired back at Paul, a doctor who had suggested in recent days that childhood vaccinations should be "voluntary." The LDP's broadside was titled "Rand Paul Takes Break From Vaccine Denialism to Endorse David Vitter For Governor."