This new survey from Muhlenberg caused a minor earthquake in political media when it dropped on Saturday night, not because it showed a major change in the race but because it didn’t. Everyone, me included, expected that the first poll of Pennsylvania in nearly two weeks would capture the same dynamic as every other poll over the last 10 days — a much tighter race all of a sudden, possibly even with Trump in the lead. Late last week, a friend who’s politically connected told me that he’d seen a private poll of PA that showed the election there a dead heat. If and when a public poll replicated that, the media was destined to have a total meltdown. Pennsylvania, after all, is supposed to be Clinton’s firewall; so long as she’s leading comfortably there and in New Hampshire, it’s difficult to the point of near impossibility for Trump to scrape together 270 electoral votes. If she isn’t leading comfortably there then all bets are off and Democratic confidence in the outcome this fall will completely collapse. The entirety of political media was, and to some extent still is, waiting for the Pennsylvania shoe to drop and a thousand “JUMP BALL” headlines to bloom.

Then the shoe finally dropped. Result: Hillary landslide. W-w-w-wut?

How’s she doing it? Partly through her familiar advantages among women, college grads, and the entire population of Philadelphia, but also through a very odd falloff in Republican support for Trump:

A critical challenge lies within his own party: 71 percent of Republicans say they’re backing Trump, while 10 percent back Clinton and 19 percent are unsure. Among Democrats, 81 percent are for Clinton, 11 percent are for Trump and 9 percent are uncertain.

Independents lean toward Clinton, 42 percent to 33 percent, and one-quarter are undecided.

Just 71 percent of Republicans in Pennsylvania are backing Trump at a moment when he’s newly competitive in other battleground states, knowing full well that his presidential chances hinge on their support? That seems mighty outlier-ish to me. In fact, 32 percent in the four-way race is by far Trump’s worst number in Pennsylvania this year. He’s trailed in every poll (apart from one flukey Quinnipiac survey in late June that had him up six) but he hasn’t been below 36 percent since August. By the same token, Gary Johnson had never done better than nine points there before — and now suddenly he’s at 14 percent. Muhlenberg’s data would seemingly have you believe that some critical chunk of GOP voters are abandoning Trump for the libertarian right at the moment that Hillary Clinton is faltering and the state looks like it could be in play. At 40 percent here, Hillary’s share of the vote is easily the lowest she’s had in any PA poll since August. (Her previous low was 44.) Muhlenberg is, in other words, detecting the same sort of deterioration in support for Clinton this month that many other pollsters have. It’s just that they’re picking up an even worse deterioration for Trump. They’re far outside the herd on that.

The problem with dismissing Muhlenberg as an outlier is that the margin it has for Clinton is entirely consistent with what the last few months of polling in Pennsylvania have showed. The last four polls there before this one, dating back to late August, had her ahead by eight points, five points, eight points, and five points. Now Muhlenberg has her up eight again. That doesn’t jibe with Trump’s surge in other swing states, but then there’s no reason to believe that each individual swing state will swing the same way. Over the weekend my pal Karl offered a compare-and-contrast of the RCP poll averages in Ohio, Florida, and Pennsylvania over the last few months. All summer long, even when he was stuck in the doldrums in August, Trump has been within four points of Clinton in the four-way race in Ohio. Same goes for Florida: Even at the height of her convention bounce, Clinton was doing no better than a four-point lead over Trump there.

Pennsylvania, though? Insert fart noise here:

An eight-point lead for Clinton with Trump at 32 percent still seems borderline preposterous under the circumstances, but you can see clearly there why Pennsylvania polling might not reliably track polling in Ohio and Florida. The blue wall in PA is sturdier. (Per WaPo, Clinton’s team is pessimistic about winning Ohio and Iowa and expects Florida to be competitive to the end.) It may be that Trump did briefly surge in the state earlier this month and has now faded again, and the surge didn’t show up in the polls simply due to the quirk that no one was conducting a survey there at the time. Or it may be that something is off with Muhlenberg’s likely voter screen and they’re not picking up the full extent of support for Trump in rural areas. Obviously he’s going to do considerably better than 32 percent on Election Day. But then, Hillary’s going to do better than 40 percent too.

Although maybe not a lot better. While we’re talking about polling, wrap your mind around how quickly and how deeply her support among younger voters has disintegrated nationally over the last few weeks:

Among those under age 35, Mrs. Clinton’s lead over Republican presidential rival Donald Trump fell from 24 points in late August to just 5 points this month in Quinnipiac surveys. That was one reason her overall lead among likely voters fell from 7 points to 2 points.

Similarly, Mrs. Clinton bested Mr. Trump by 27 points among voters under 35 in a Fox News survey in early August. That lead fell to 9 points in a new Fox News survey.

The trend is appearing in some state-level surveys, as well: In a new poll of Michigan voters, Mrs. Clinton’s 24-point lead among young voters a month ago fell to 7 points.

Double-digit decline in multiple polls in just a few weeks among the same demographic is an eye-popping problem for Team Hillary. Some of the decline is due to her convention bounce fading, but surely not all of it. What’s happened lately to alienate younger adults from her? Neither the “deplorables” comment or her fainting at the 9/11 event have any obvious particular resonance for under-35 voters. Have they just caught Gary fever? Whatever the explanation, it’s surprising.