The inclusion of those delegates allows Trump to cross several threshholds, including his winning more than 50% of the delegates so far and increasing the possibility that the candidate will arrive in Cleveland with more than the 1,237 delegates needed for a first ballot victory.

At least 36 delegates in Pennsylvania who were previously "unbound" to any candidate have pledged their support for Donald Trump, according to analysis by the Washington Times.

“I don’t think it gets to a second ballot anymore. I think he is the presumptive nominee,” said Mike Puppio, the chairman of the Springfield Republican Party who won a seat as a delegate from Pennsylvania’s 7th Congressional District, and who said he’ll now support Mr. Trumpbecause the billionaire businessman won the popular vote in his district. Going into Tuesday, Mr. Trump had won about 45 percent of all delegates awarded. But his massive wins in Pennsylvania, Maryland, Delaware, Connecticut and Rhode Island earned him most of the 172 delegates at stake. He is now nearing 1,000 delegates overall and is more than 400 ahead of Sen. Ted Cruz, his closest competitor. Ohio Gov. John Kasich, the third major candidate still in the race, trails far behind with only about 160 delegates. He’s even still behind Sen. Marco Rubio, who has won more than 170 delegates despite having dropped out of the race nearly a month and a half ago. Mr. Trump proclaimed himself the “presumptive nominee” on Tuesday night, and analysts and activists said he’s probably justified after notching the kinds of margins a clear front-runner should be tallying at this point in the race. “The fat lady may not be singing, but she’s certainly on stage, and I’m just waiting for Donald Trump to make fun of her weight,” said Charlie Gerow, a GOP strategist in Pennsylvania who ran to be both a delegate and an alternate. He lost the delegate race to a slate of three avowed Trumpsupporters but did earn an alternate’s post. He said Mr. Cruz does have a chance to derail Mr. Trump in Indiana, which votes next Tuesday, but soon after that the conversation will shift to the inevitability of Mr. Trump. That’s when more free agent delegates will begin to announce they’ll support the front-runner at the convention.

There are about 200 unbound delegates who are currently up for grabs. The more Trump wins, the better his case for those delegates backing him on the first ballot to give him the nomination.

I still think it likely that Trump arrives in Cleveland a couple of dozen delegates short of a majority. The primary calendar is moving into some states that won't be as friendly to Trump as those in the northeast. Trump may still win, but he needs more than 50% in many of those states to trigger the "winner take all" rule.

While it's probable for that reason that Trump comes up a little short, it's also probable that the unbound delegates break heavily for him, putting him over the top.

Everybody likes to back the winner, and avoiding a messy floor fight will be one of the things uppermost in the minds of free agent delegates. There may not be much unity at the convention, but at this point, Trump appears in no danger of having the nomination taken away from him.