Polling analyst Nate Silver REPORTS tonight:
[T]he fact that the national polls now suggest a slight lead for Mr. Obama removes one of the better reasons to think that our forecast might have been underrating Mr. Romney’s chances.
Based on the simulations that we ran on early Sunday evening, for example, Mr. Obama would have an 85 percent chance of winning the Electoral College if the popular vote were exactly tied nationally. This is where Mr. Obama’s Electoral College advantages, particularly in Nevada, Ohio and Wisconsin, would be of their maximum benefit. Given a tied national popular vote, we would expect Mr. Obama to underperform his polls slightly in these states — but since he leads by a minimum of about three points in the polling average in each one, he could underperform those numbers and still win them.
Mr. Obama would be almost certain to win the Electoral College if he won the popular vote by a percentage point or so.
Mr. Romney would not be in much danger of losing the Electoral College if he won the popular vote by more than about 1.5 percentage points. For example, he would be about a 95 percent favorite in the Electoral College if he won the popular vote by two percentage points, according to the forecast model.
But with national polls now showing a slight edge for Mr. Obama, these outcomes have become less likely. If Mr. Romney wins the popular vote, it may be only barely, and that might not be enough for him to win the Electoral College.
UPDATE (10:35 p.m.): Steve Singiser over at Daily Kos Elections has THIS:
[B]y and large, it is hard for Democrats not to be encouraged by the avalanche of numbers cascading down this weekend.
For the first time in a long time, there is a semi-consensus in the national polls, and it is good news for the incumbent. Despite some wildly variable individual polling in the state surveys, the critical mass of data points to a considerably easier path to 270 electoral votes for President Obama than it does for Mitt Romney.
As many have long suspected, there has been a bit of a convergence in this final weekend between the national polls and the state polls. While the state polls have actually remained pretty consistent, there has been a small-yet-clear movement in the national polls in the direction of the president.
For the fifth day in a row, President Obama enjoys an incremental lead in the average of national tracking polls. Today, however, is his largest lead in those five days, and his largest lead since immediately after the Denver debate. The ten national polls today yielded a lead of 1.5 percentage points for Obama, which comes close to matching the high point of the “Mitt-mentum” that immediately proceeded that Denver debate, but dissipated a few weeks ago (long before pundits actually started to notice, as it were).
At the electoral college level, the dilemma for Mitt Romney continues to be finding a reliable path to 270 electoral votes. Sure, there are stray wild polls (almost all conducted by GOP pollsters) which show him with numbers to contend with in places like Michigan, Minnesota, Pennsylvania, and New Hampshire.
At this late stage of the game, the conclusion seems to be clear: for Romney to win, the polls have to be off. Systematically, in multiple states, and probably by several points. Clearly, Republicans are counting on that fact. Just as clearly, there is essentially no precedent for it. There are cases where individual states have been way off the fairway (Indiana in 2008 is an instructive example–Obama only led in a tiny fraction of Hoosier State polls). But across the board? This would be the first time.