Pennsylvania
RCP Average
Two-Way... Clinton 43 Trump 42
Four-Way... Clinton 40 Trump 38 Johnson 7.5 Stein 3.5
Most recent
Quinnipiac Two-Way... Clinton 42 Trump 41
Quinnipiac Four-Way... Clinton 39 Trump 36 Johnson 9 Stein 4
There are very few and relatively spaced apart individual state polls that do both the 2 way and 4 way. If the above is an indication, 8 points from Clinton and Trump shift to Johnson/Stein. Hillary loses 3 and Trump loses 5.
That's a single state and I don't know that the pattern will hold. In FL, VA, OH... they each have only a single recent poll, so you can't judge the effect. My suspicion is that a variation on the polls in PA will hold true. There are more disgruntled Republicans who will move to Johnson than there are disgruntled Dems who will move to either Stein or Johnson. Both Stein and Johnson in the Quinnipiac poll are picking up a portion of the uncommitted. Total is 83 per cent vs. 88.
Aside: There's other bad news for the GOP. Look at NC. Without the other two parties, Trump's ahead. With the L and G parties, it's a dead heat. I'm not a believer in AZ coming back into play - it's too "red". But if NC goes Democrat again, coupled with VA and PA and MI, we won't have to listen to CNN talk all night about "it all comes down to Florida and Ohio".