On Friday my state polls were 0.6% above national and now 1.0%. Why do I think the national is closer? There are 14 heavily polled states. 538 lists 16 states on the side of their national page, but I excluded Maine, Minnesota, and Utah because they're not heavily polled and included Missouri, which has been. For my election result in most of the remaining 37 states and DC I'm using Internet only polls with an occasional traditional poll in there. In some cases my traditional poll is older than swing state polls and the I really question the accuracy of Internet polls.
So I totaled the vote if only the 14 most commonly polled swing states were used. Clinton leads in them by 1.1%, compared to Barack Obama winning them by 1.7%. Obama won by 3.8% in 2012. If Clinton is doing 0.6% worse she has a 3.2% lead, a bit worse than the 3.7% lead 538 gives her. I don't think it's that low, as Trump seems to be doing better in swing states than in non-swing states. It's conceivable that Clinton could win by less than Barack Obama did in 2012 but win by more in California. If Clinton wins California by 3.0% more her overall margin moves roughly 0.3% toward her. If she wins the election by 0.6% less than Barack Obama, that means Trump needs to make up the 0.9% in other states.
A number of these swing states appear tight. If Trump chisels Clinton's lead by even 2% more, he could conceivably win while losing the popular vote.