Donald Trump had a big night last night; as expected he swept the five states in the “Acela Primary”. What made the night special for Trump was two things. First, market-based forecasts had him at 40% to win all five state with 50% or more of the vote. So, Trump’s 58% in CT, 61% DE, 54% in MD, 57% in PA, and 64% in RI was bigger than expected. Second, Trump did well in securing the “pledges” of unbound delegates in Pennsylvania. While the final number is not yet clear, between delegates saying they will vote for him or vote for winner of Congressional District, he should get well more than half of the 54 unbound delegates on the first ballot at the convention.
So, it is not surprising that Trump surged last night from 75% to win the nomination to 83% this morning. Most of this probability came at the expensive of Ted Cruz, because he is the only one left to give!
More technically, Trump is now 66% to reach the magic number of 1,237 pledged delegates. But, he is 79% to win the on the first ballot. The markets have been clear about this for months now; Trump does not need 1,237 pledged delegates to win. He needs closer to 1,200 pledged delegates, depending on how the unbound delegates are counted (here we are using the AP totals). Beyond Pennsylvania there are going to be 100+ completely unbound delegates, some of whom will vote for Trump in the first ballot. At this point, should he somehow lose the first ballot, he will be highly unlikely to win the nomination on a subsequent ballot.
The Cruz and John Kasich pact has so far failed to stop Trump in Indiana. He is 70% likely to win as of this morning, up from about 67% when the non-aggression pact was announced. It is hard for alliances to hold, if voters head the call many Kasich voters would jump to Cruz or Trump, and it is hard to get voters to vote strategically. A win in Indiana would be huuge for Trump, but not necessary to get the nomination.
Also, Hillary Clinton is now 98% to win the Democratic nomination.