RCP Poll averages say Obama is leading McCain in Pennsylvania 51percent to 44 percent.
The Pew Research Center's final pre-election poll of likely voters in the U.S. finds 49 percent supporting or leaning to Obama, 42 percent for McCain; 2 precent for minor party candidates and 7 percent undecided.
When the undecided vote is allocated, Obama holds a 52 percent to 46 percent lead over McCain.
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The Republican candidate has also made gains among political independents and middle-income voters.
Obama still maintains a modest lead among independents, while middle-income voters are now evenly divided.
A Pew survey finds indications that turnout may be significantly higher than in 2004, when voting participation reached its highest point in nearly four decades.
The new poll projects increased rates of voting among young people and African Americans, who strongly favor Obama. But it also finds signs of greater likely turnout across the board.