Some improvements from Andrew Ferguson: The update date/time above now links to the history graph, and the Obama/Romney numbers link to the map.&...
We are repairing a problem in our HuffPollster feed. We were not scraping states with few polls, and in those cases were using 2012 election results. This is now corrected. Current polls make the following states closer by at least three percentage points compared with 2012: AR, CO, CT, KS, ME, TN, TX, and WA. In addition, Nevada is now flipped to Trump +7% (one poll only). As a result, the EV estimator takes a jump today, as well as the Meta-Margin (from Clinton +3.9% to Clinton +3.3%). This is not a real jump, but a correction to make sure that all polls are included. I apologize for the error. (Update, July 8th: the history has been recalculated using the correct data. The jump is now gone.)
These corrections reflect a general phenomenon in which both parties’ candidates are underperforming compared to 2012, perhaps because of undecided voters. In early July 2012, approximately 90.7 +/- 1.1% (mean +/- SEM) of voters reported a preference for Obama or Romney. In 2016, total Clinton+Trump support is currently 85.2 +/- 2.0%. This year’s reduction in decided voters may reflect reduced enthusiasm for the candidates, particularly Donald Trump, who is notably weak in strongly Republican states. More on this later.