Pennsylvania, though, is important to Trump because it is the best example of a state that Trump says he should win: Blue (but trending toward swing status), and with a lot of working-class white voters and blue-collar Democrats whom Trump can draw to the polls.

That's not how Suffolk's poll looks.

Trump leads with men in the state, though barely. Clinton leads with women by a wide margin. Each gets most of the support from their party's voters, but not all.

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And there's the problem for Trump.

Clinton gets 83 percent of the votes of Democrats, losing 13 percent to Trump. That's a big chunk: Losing 1 of every 10 members of your own party is out of step with recent presidential results. Trump loses slightly fewer, 11 percent — really about the same once you consider the margin of error. But he gets only 76 percent of Republican votes — almost certainly thanks in part to how poorly he does with women.

That's Trump's challenge. Maybe he can grab some of the moderate white men who are still in the Democratic Party, a group that was already nearly tapped out by the time Ronald Reagan sought reelection. But if he loses moderate Republican women — still a big group — it's a net negative. Republicans have won white women in every election but two since 1972, the two exceptions being the races won by Bill Clinton in 1992 and 1996. If Trump loses a big chunk of that vote, or even underperforms significantly relative to past Republican candidates, it's very hard to see how he could win.

The standard warning applies: This is one poll, in one state. But it's something to watch.