Democrats were probably feeling a sigh of relief last week when three major national polls were released over the course of three days, each of which showed Hillary Clinton leading Donald Trump by six points, even with third-party candidates in the mix. As of this morning, however, that sense of relief has all but disappeared.Three national polls have been released over the last 24 hours, and each show Clinton's lead evaporating. Let's start with the Washington Post/ABC News poll, released yesterday morning.Four-way race: Clinton 46%, Trump 44%Head-to-head match-up: Clinton 49%, Trump 47%This was soon followed by the new Bloomberg Politics poll:Four-way race: Trump 43%, Clinton 41%Head-to-head match-up: Clinton 46%, Trump 46%And the new Quinnipiac poll:Four-way race: Clinton 44%, Trump 43%Head-to-head match-up: Clinton 47%, Trump 46%On the day of the first debate, in other words, the presidential race is effectively a dead heat. For all the easy assumptions -- so many have argued, "The United States just isn't the kind of country that would elect a racist television personality to be president" -- there's no denying the unavoidable fact that Donald J. Trump has a decent chance of winning the 2016 election.Indeed, the latest state polling will only intensify the hand-wringing. The latest Morning Call/Muhlenberg poll in Pennsylvania, for example, shows Clinton's advantage in the state shrinking to just three points. A CNN poll out this morning puts Clinton's lead in Pennsylvania at just one point.CNN also polled voters in Colorado -- generally seen as a likely "blue" state -- and found Trump actually taking the lead in the Rocky Mountain State, 42% to 41%.The New York Times' predictive model, meanwhile, shows Clinton with a 69% chance of winning the presidential election, which is down quite a bit from 90% a month ago. FiveThirtyEight's election forecast shows Clinton with a roughly 52% chance of success, down from 80% in early August.Following up on a piece from a couple of weeks ago, I'm not sure what more it would take to motivate voters. If you want Trump to win, there’s fresh evidence that your preferred candidate is well within striking distance of actually getting elected. If you want Clinton to win, you can no longer assume this race is in the bag -- you and your allies are going to have to go earn it.Election Day is in 43 days. Early voting has already begun in several states.