The Los Angeles Times said Saturday the Election Day margin of just over 2 percent has gradually widened out to nearly 4 percent.
The Cook Political Report Friday gave Obama 50.97 percent of the popular vote to Mitt Romney's 47.3 percent. The totals include 47 states where the results have been certified as final.
Cook's David Wasserman told the Times the majority of the estimated 413,000 uncounted ballots were mainly in New York, a state that leaned heavily Democratic.
The Times said if Obama surpassed 51 percent of the popular vote, he would be only the fifth president in U.S. history to win election twice with 51 percent of the vote.