Harry Enten sees the next two weeks as pivotal:
[T]here is no guarantee that Romney will jump into the lead following the Republican National Convention. On the other hand, even a 1-point boost for Romney nationally would bring this race to near parity. A small bounce would also suggest the electorate is not static and will shift allegiances under the right circumstances.
No shift would portend very bad news for Romney. The explanatory power of polls jumps considerably after the conventions. If Obama still leads by 1.5 points once the convention dust has settled, it’s difficult for me to envisage how Obama will lose. Conventions are typically the one campaign event that can have big effect on the state of the race.