After a series of daily tracking polls in which Barack Obama was running even with John McCain, Gallup says its June 6-8 survey has Obama leading by 48 percent to 42 percent. The margin of error is 2 percent. Gallup attributes this bump to Hillary Clinton’s exit from the race. Fifty-three percent of Democrats told the pollster that Obama should choose Clinton as his running mate while 36 percent said he should not. Gallup says the choice of Clinton would add three points to Obama’s margin.