Early voters could account for up to 40 percent of all ballots cast in the 2012 U.S. 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 November 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. The sample size of early voters is 960 people with a credibility interval of plus or minus 3.5 percentage points....

As a sign of the importance the Democrats place on early voting, Obama became the first sitting president to vote early when he cast his ballot in Chicago on Thursday.

The two parties spent a lot of time in court this year battling over early voting laws in states such as Florida and Ohio as Democrats accused Republicans of trying to limit early voting to suppress the turnout of working-class and minority voters.

In the end, Ohio was ordered by the courts to allow early voting to all until the eve of the election. And while Florida cut the number of days of early voting, it agreed to extend the number of hours on each day to satisfy critics.

Hardly surprising and fairly irrelevant. Ohio makes or breaks this election.