Trump's Biggest Wins On Tuesday Were These Obscure Races In Pennsylvania

Donald Trump was remarkably dominant in Tuesday's Republican presidential primaries, sweeping Connecticut, Delaware, Maryland, Pennsylvania and Rhode Island handily. But his biggest victory may have been in a bunch of tiny contests in Pennsylvania that you may not have known were happening. And those wins show how the Trump campaign -- and the race itself -- is changing.

Most people who've been following the race for the GOP nomination know it isn't just about winning votes -- it's also a race for delegates. The majority of the delegates awarded Tuesday were bound delegates -- that is, they are required to vote for their assigned candidate on the first ballot at the Republican National Convention in July. Trump did well on that front Tuesday, taking home more of the bound delegates at stake than most pundits predicted. 

But where Trump really outperformed Tuesday was in his quest for unbound delegates -- which, by a weird quirk of primary rules, are particularly common in Pennsylvania. 

The majority of Pennsylvania's 71 GOP delegates -- 54 of them -- are unbound, and free to vote their consciences at the convention, much like Democratic superdelegates . (The other 17 delegates are bound to vote for the statewide winner -- in this case, Trump.) This gets complicated, but it will make a big difference in the presidential race, so stay with me.

In Pennsylvania, unbound delegates are elected directly -- their names are on the ballot. Republican primary voters in each of the state's 18 congressional districts each vote for three delegates to the convention.

Unbound delegates often run as members of slates backing particular candidates. But the presidential candidate each delegate is backing is not listed next to the delegate's name on the ballot. That means presidential candidates have to recruit potential delegates to run and make sure that voters know that, say, a vote for an unbound delegate named John Smith is really a vote for Texas Sen. Ted Cruz. 

In Pennsylvania's 11th Congressional District, for example, GOP primary voters didn't just have to pick among Cruz, Trump, or Ohio Gov. John Kasich. They also had to choose three delegates out of a field of 15 candidates -- most, if not all, of whom they'd probably never heard of. 

Making sure voters knew which delegates they had to vote for to help Trump was an immense organizational and logistical challenge for the Trump campaign, which is better known for attracting media attention than for its attention to the intricate rules of the nominating process . (The Trump campaign has consistently performed poorly in caucus states, which require more organizing than primaries, for example.) But this time, they seem to have done it. Voters across Pennsylvania received mailers letting them know which delegates were on the Trump slate:

The Trump campaign handed out fliers with its delegate slate at campaign events . Some voters received mailers urging them to vote for Trump's delegates in their congressional district:

All that voter information seems to have worked. Trump's slate should win at least 29 of Pennsylvania's 54 unbound delegates, The New York Times' Nate Cohn estimated  Wednesday morning. Additionally, 13 of the delegate candidates who were leading late Tuesday night have promised to vote for the candidate who won their congressional district -- which, given his near-clean sweep of the state, will almost certainly be Trump. That means Trump will take far more than just Pennsylvania's 17 pledged delegates to the convention. 

Those 40-some-odd delegates could make a huge difference in the outcome of the race. Trump's the only Republican candidate left with a chance of winning an outright majority of delegates before the convention. Cruz and Kasich are trying to block him from getting to that magic number, 1,237. The 40 or so unbound delegates from Pennsylvania could be the difference.

Now, Trump just has to hope they keep their promises.

Editor's note: Donald Trump regularly incites political violence and is a serial liar , rampant xenophobe , racist , misogynist and birther who has repeatedly pledged to ban all Muslims -- 1.6 billion members of an entire religion -- from entering the U.S.

This article has been updated with additional polling information.