WASHINGTON -- President Barack Obama continues to hold narrow leads in a handful of battleground states that will likely decide the election, but some argue that Republican nominee Mitt Romney will come out on top because Obama's poll totals linger just below 50 percent.The arguments are based on what campaign pollsters used to call the "incumbent rule," the idea that when an officeholder seeks reelection, undecided voters would break decisively to challengers in the final days of the campaign.