Heads turned yesterday at the size of the advantage among women for President Obama in new Gallup/USA Today national and swing state polling. A closer look at the results shows that Obama's gender gap is concentrated among groups that have favored him in the past, which could make it tougher for Mitt Romney to overcome his advantage. Gallup released two surveys. One was a national poll, which showed Obama leading Romney, the presumptive GOP nominee, by 49 percent to 45 percent among registered voters. In a second poll, Obama led Romney by 51 percent to 42 percent among registered voters in 12 key swing states. In both polls, Obama and Romney ran about even about men. The president's advantage was driven almost entirely by women, who provided him a resounding double-digit advantage in both surveys. But a closer look showed women also dividing along lines familiar from recent elections.