CHICAGO — A couple blocks outside of the Democratic National Convention’s United Center, a few passersby stopped to watch a lip-syncing man dance atop a bus plastered with a meme-ified, sunglasses-wearing image of independent president candidate Robert F. Kennedy Jr. But was this little more than a bizarre swan song? Earlier Tuesday, Kennedy’s vice presidential running mate, Nicole Shanahan, told a podcast that the Kennedy campaign is considering quitting the race and throwing its support behind Republican presidential nominee Donald Trump. Want more breaking political news? Click for the late…