Donald Trump Secures Vast Majority of Unbound Delegates in Pennsylvania

— -- Donald Trump has won a vast majority of the unbound delegate count in the state of Pennsylvania, according to an ABC News analysis. Of the 54 available free-agent delegates in the state, 28 said they will support the Republican front-runner, while 13 additional delegates -- who said they would vote for the winner of their congressional district on the first ballot -- will also back Trump.

Only three delegates said they plan to vote for Cruz on the first ballot. Nine others are uncommitted.

While Trump won a resounding victory in Pennsylvania's popular vote Tuesday night, it was not assured that he would walk away with all of the state's 71 delegate votes because of the state's unusual delegation selection process.

Only 17 of the state's delegates are bound to vote for Trump on the first ballot, while voters directly elected the other 54 — three from each of the state's 18 congressional districts – to act as free agents at the convention.

Trump argued on Tuesday night that delegates have a "moral obligation" to support him on the first ballot as the winner of the state's popular vote.

"There's a moral obligation, at least on the first round, to support the person that won," Trump said in a victory speech on Tuesday night. "Now, we didn't only win, we won big."

But some outstanding delegates aren’t so sure.

Aaron Cohen, a delegate elected in the Pennsylvania's 2nd district, ran as uncommitted and has yet to declare who he will support, but told ABC News Tuesday night he will "probably…not support Trump."

While results were still coming at the time of Cohen's interview, he said he'd "have to evaluate" what he'd do at the convention if Trump is the resounding winner of both his district and the statewide vote.

But James Klein, who was elected in the 5th district and ran as a Trump supporter, told ABC News Monday that he is "wall-to-wall Trump."

"It's time for the party to begin to see the reality here and bring itself together," Klein said.

Wayne Buckwalter, a 6th district delegate who plans to vote for Trump on the first ballot, told ABC that he expected a Trump blowout.

"The suicide pact with Cruz and Kasich sabotaged themselves," he said. "That proved that the system is rigged against Trump."

Pennsylvania represents the largest potential delegate haul of the 136 total unbound delegates who will be free to vote for whomever they choose on the first ballot, likely holding the power the tip the scales in a tight convention.

ABC News' Jim Hill, Lauren Pearle, Jessica Puckett, John Kruzel, and Alana Abramson contributed to this report.