By Sept. 17, the date when the video of Mr. Romney's remarks was released and received widespread attention, the momentum from Mr. Obama's convention appeared to have stalled (although not necessarily reversed itself). Mr. Obama led in the popular vote by 4.1 percentage points on that date, according to the "now-cast."Since then, however, Mr. Obama has gained further ground in the polls. As of Thursday, he led in the popular vote by 5.7 percentage points in the "now-cast," a gain of 1.6 percentage points since Mr. Romney's remarks became known to the public.It's hard to tell whether this recent gain for Mr. Obama reflects the effect of the "47 percent" comments specifically. But the most typical pattern after a party convention is that a candidate who gains ground in the polls cedes at least some of it back.Instead, the more pertinent question seems not whether Mr. Obama is losing ground, but whether he is still gaining it.