Updated to include Mellman poll. The average of October polls of likely voters puts Steve Bullock and Rick Hill in a functional tie — Bullock leads by 0.2 percent. There is, however, considerable volatility in the numbers. One of the most recent polls, conducted for the Lee newspapers by the Mason-Dixon firm, put Hill ahead by three points; the other, conducted by the Mellman Group, using a larger sample, put Bullock ahead by seven points with 10 percent undecided.
As I noted yesterday, Tester’s campaign challenges the accuracy of the Mason-Dixon poll, a challenge that I suspect means Tester’s internal polling puts him in the lead. And Mason-Dixon’s results do differ markedly from those of other polls almost as recent. As Nate Silver explained in Friday’s New York Times, polls differ for a number of reasons. We won’t know whether Mason-Dixon or Mellman, both reputable firms, got Montana right until after the election.
Below, two graphs. The first presents the overview for September–October. The second presents a high resolution view of Bullock’s lead over Hill. In this graph, a lead can be a negative number.
