On Thursday, Franklin & Marshall released a new poll of Pennsylvania's Democratic Senate primary that sharply contradicts a Monmouth survey from just a day earlier that found the contest tied at 39 apiece. Instead, F&M continues to see ex-Rep. Joe Sestak leading former state cabinet secretary Katie McGinty, by a margin of 38-29 among likely voters.
In response, McGinty shared an internal poll with Politico Pro, but since it's behind their paywall, all we know are the supposed toplines, which have McGinty ahead 37-34. (We've asked the campaign for the name of the pollster, the field dates, and the sample size but have not heard back.) A super PAC supporting Sestak called Accountable Leadership fired back in turn with a poll of its own from Prism Surveys that looks a lot like F&M's, giving Sestak a 38-31 lead.
F&M, though, is a notoriously balky pollster. Their most frequent failing is their huge numbers of undecideds. Indeed, in their last poll, taken just a month ago, they had Sestak in front 31-14, with fully 46 percent of respondents saying they hadn't made up their minds, a much higher proportion than other outfits have ever found in this race. F&M's latest numbers don't suffer from quite the same issue (here, "only" 25 percent are undecided), but Nate Cohn notes another problem: The sample appears to be far too old.
That might explain why F&M shows Hillary Clinton leading Bernie Sanders, who has done very well with younger voters, by a 58-31 spread in the presidential race, whereas Monmouth, which had a more balanced sample age-wise, had Clinton up by a smaller 52-39 margin. It's hard to say which school is right, though, since there hasn't been much fresh polling out of Pennsylvania, and presidential numbers weren't included with either of the two internal polls. But we'll finally have our answers soon enough.