As we mentioned earlier Monday, Gallup's post-debate survey suggested that Mitt Romney's strong performance in Denver had helped him close the gap between him and the president in the polls. Before the debate, the Republican trailed the incumbent by 4 points in Gallup's seven-day rolling average, but by Saturday that gap had shrunk to 3 points.
If you broke the data down further and compared only the three days before the debate to the three days following it, things looked even more promising for Romney: a 5-point Obama lead disappeared to leave the two men tied at 47 percent apiece.
But Gallup's since updated its seven-day rolling average to include Sunday's polling, and what a difference a day makes. Obama's now back up five points, 50 percent to 45 percent.
We'll state the obvious here: The polling averages are clearly fluid and it's probably best not to read too much into a tick or two in either direction. But the margin of error is 2 percentage points in either direction (so roughly 4 points when talking about the gap between the two candidates), so the current polling has the president's lead back outside of that margin of error range.