Pennsylvania’s delegate allocation process is one of the oddest in the whole country. While Pennsylvania will technically hold a voting primary next Tuesday that will officially decide a handful of delegates, by far the bulk of Pennsylvania’s delegates will be totally and completely unbound.
That having been said, the effect of the primary vote will have at least some theoretical impact on the extent to which some delegates will be subject to public pressure. Some potential delegates have already explicitly said that they will vote for whoever wins their congressional district. Others have explicitly said they will vote their conscience either way.
The polling for Trump in Pennsylvania had been trending towards 45% or even 50%, which was at least going to offer Trump a compelling case to come to the 50+ unbound delegates in Pennsylvania and make his case that they should all vote for him or face the wrath of their constituents.
On the other hand, the latest poll from Pennsylvania, from Franklin and Marshall, shows Trump checking in at a mere 40%, with Cruz and Kasich getting 26% and 24%, respectively. Obviously, there’s a lot of reason to distrust polls at this point in the game; prior to New York, they had systematically overstated Trump’s support, but in New York, they way understated it.
At the end of the day, there is no realistic way for Trump to reach the 50% delegate threshold without a pretty sizeable chunk of the Pennsylvania unpledged delegates. And if he registers only 40% statewide in Pennsylvania, it will be much easier for all of them to abandon him than it will if he gets 50% or close to it.