We began November with Democrats confident that demographics and low unemployment guarantee Hillary Clinton’s election. We end it with fears of terrorism and infiltration, with Democrats no longer as sure.

This reversal should give pause to any commentator. If the situation is so fluid now, how can we say with any confidence what things will look like a year on? Elections come into focus late. Why? Because most voters don’t pay attention to politics until the balloting is imminent.

Some examples. George W. Bush led Al Gore for much of 2000. But the race closed in the last week after reports of Bush’s past cocaine use. What looked like a sure Bush victory surprisingly turned into the Florida recount.

When September 2008 began, John McCain was in a close race with Barack Obama. Sarah Palin infused the Republican ticket with youth and populist energy, Russia’s invasion of Georgia had played into McCain’s national security expertise, and high gas prices occasioned calls for “Drill, Baby Drill!” The next month Lehman Brothers collapsed, money market funds plunged into crisis, and the global financial system froze. McCain was doomed.