Nate Silver writes: Hillary Clinton’s lead in the polls has been declining for several weeks, and now we’re at the point where it’s not much of a lead at all. National polls show Clinton only 1 or 2 percentage points ahead of Donald Trump, on average. And the state polling situation isn’t really any better for her. On Thursday alone, polls were released showing Clinton behind in Ohio, Iowa and Colorado — and with narrow, 3-point leads in Michigan and Virginia, two states once thought to be relatively safe for her.
It’s also become clearer that Clinton’s “bad weekend” — which included describing half of Trump supporters as a “basket of deplorables” on Friday, and a health scare (followed by news that she had been diagnosed with pneumonia) on Sunday — has affected the polls. Prior to the weekend, Clinton’s decline had appeared to be leveling off, with the race settling into a Clinton lead of 3 or 4 percentage points. But over the past seven days, Clinton’s win probability has declined from 70 percent to 60 percent in our polls-only forecast and by a similar amount, from 68 percent to 59 percent, in our polls-plus forecast.
That’s not to imply the events of the weekend were necessarily catastrophic for Clinton: In the grand scheme of things, they might not matter all that much (although polling from YouGov suggests that Clinton’s health is in fact a concern to voters). But when you’re only ahead by 3 or 4 points, and when some sequence of events causes you to lose another 1 or 2 points, the Electoral College probabilities can shift pretty rapidly. [Continue reading…]