We won’t know for another day or two if this weeks’ polling results are due to outliers, but Gallup’s latest 7-day tracking poll of likely voters is out and it shows the race narrowing slightly from 52-45 to 51-45. Their poll of registered voters has flattened quite a bit too. For the second day in a row it shows Romney with a 48-47 advantage. That poll is in line with other organizations which show about a 1-point Romney lead. Much of Mitt Romney’s advantage, therefore, is likely due to how Gallup screens for likely voters. As I wrote yesterday evening, the widening lead among those likely to cast a ballot is likely attributable to more “broken glass voters” on the Republican side.