WASHINGTON - Early voters could account for up to 40 percent of all ballots cast in the 2012 US presidential election, and polls of people who already voted show President Barack Obama with a comfortable lead over Republican challenger Mitt Romney.
Both candidates have been urging supporters not just to vote but to do it early as Republicans and Democrats campaign vigorously - particularly in key battleground states - to lock up as many votes as possible before Election Day on Nov 6.
Polls of people who say they already have voted show Obama with a lead in many of the states. The Obama campaign, which benefited from early voting in 2008, has focused heavily on urging supporters to vote early in this election as well.
Obama leads Romney 54 percent to 39 percent among voters who already have cast ballots, according to Reuters/Ipsos polling data compiled in recent weeks.