President Barack Obama has fired up his campaign’s efforts to get supporters to the polls by casting an early ballot in his hometown of Chicago."For all of you who have not yet early voted, I just want everybody to see what an incredibly efficient process this was,” Obama said on Thursday.Several American states allow voting before election day and polling data suggests the Democratic incumbent has built a lead over Republican challenger Mitt Romney among early voters in the run-up to November 6.The race is otherwise extremely tight nationwide, and early voting just might make the difference in some areas."It means you don’t have to figure out whether you need to take time off work, figure out how to pick up the kids and still cast your ballot,” Obama told a small crowd of poll workers and observers, in televised footage."If something happens on election day, you will have already taken care of it. If it’s bad weather, you won’t get wet. Or in Chicago, snowy.” He then joked, "I can’t tell you who I voted for.”Obama seemed cheerful and relaxed, despite being mid-way through a two-day, six-state, non-stop tour of battleground polling areas.Early voting is a major component of Obama’s mobilization strategy, and is useful for ensuring that supporters who may have trouble getting to a polling station next month end up casting their ballots.It also allows the campaign to concentrate their efforts on people who need more persuasion.Obama is the first president to cast an in-person early ballot and his rare visit home thrilled many in this predominantly African-American neighbourhood.