Donald Trump absolutely crushed it in Tuesday's Northeastern GOP primaries. He won all five states that voted. He picked up over 100 delegates. And he'll end the day fewer than 300 delegates away from the majority he needs to clinch the nomination.

Though everyone expected Trump to do well today in a region that's been strong for him, the sheer scope of his victory was still rather astonishing:

He won nearly every bound delegate that was up for grabs.

Supporters of his seemed set to win a good share of the unbound delegate slots on the Pennsylvania ballot.

Trump seemed set to top 50 percent of the vote in all five states — which, unusually for Trump, means he outperformed his polls.

Both of his remaining rivals have now been mathematically eliminated from winning the nomination on the convention's first ballot.

All that means Trump will need to win a good deal less than half of the remaining unbound and uncommitted delegates to get his majority.

Now, there are still 10 states left to vote. And it is looking more and more likely that Trump will lock that delegate majority down outright. He's ahead in recent polls of the two most important remaining states to vote — California and Indiana — and if he wins those two states handily, he gets his majority.

But make no mistake — even if Trump falls a bit short of his majority at this point, he's now clearly on track to get very close to it indeed. And the closer he gets, the more difficult it will be to deny him the nomination.

"Close" will probably be good enough for Trump

The basic facts of the Republican race are that Donald Trump has won more than delegates than any other candidate, more states than any other candidate, and more votes than any other candidate. He's also remained at the top of national polls for months.

Given those facts, regardless of what the GOP's rules allow, it will be a tough sell for the delegates to just go and nominate someone else with far less of a mandate from their party's voters.

Indeed, several polls — including one conducted by Vox and Morning Consult — show that Republican voters are inclined to believe that the person who comes in first place in the primaries should get the nomination.

And recently, there have been few signs that enough Republicans have an appetite to wage a protracted convention battle against Trump, should he emerge the clear winner in delegates and close to that majority.

Single biggest thing Trump has going for him now is this attitude taking hold in the party: https://t.co/FBuZWlErkH pic.twitter.com/8vKFihTq5U — McKay Coppins (@mckaycoppins) April 22, 2016

Furthermore, if Trump does fall just a bit short, there will be over 100 unbound or uncommitted delegates who could help put him over the top. Many of them will have been elected in Pennsylvania, a state where Trump won in a landslide, so they'll surely feel some pressure to fall behind Trump as a result.

California and Indiana are the most important remaining states to watch

Having said that, this primary season has been full of surprises so far, so it's best not to take anything for granted. There are still enough delegates at stake that a major shake-up in the race could make Trump fall quite a bit short of that majority.

So, first of all, keep an eye on Indiana's primary next Tuesday. It's the second-most important remaining state, because it's winner-take-all (partly statewide, partly by congressional district) and has still seemed like it could tip to either Trump or Cruz. Most media commentators and politicos are interpreting Indiana as a must-win for Cruz at this point — if he loses it, his campaign will be deemed entirely dead rather than just mostly dead.

For the rest of May, Nebraska is expected to give all its delegates to Cruz, Trump is expected to do well in West Virginia, and the candidates will split Oregon and Washington's delegates due to proportional allocation.

All this leads up to the final day of GOP primary voting: June 7. Trump is expected to win all New Jersey's delegates, Cruz is expected to win South Dakota and Montana, and New Mexico is another proportional state where the delegates will be split.

But the day's biggest prize, and the state that will likely determine whether Trump clinches his majority, is California. There are 172 delegates at stake there, and 159 of them will be allotted winner-take-all on the congressional district level (3 delegates in each of the state's 53 districts) — which means that broad strength across the state will be necessary to pick up most of its delegates.

So, technically, there's still time for a major change in the race to turn things around. But if things keep going as they are, Trump's got this.