IT'S ALMOST OVER: Donald Trump is well-positioned to lock up the GOP nomination before the convention

After Tuesday's voting, in which Donald Trump won four states but not Ohio, you may have heard from some pundits that the Republican Party is headed to a contested convention. No candidate will manage a majority of delegates, meaning that they will have to fight over the nomination in Cleveland.

This is probably wrong.

If you look closely at the delegate-allocation rules, you can see that Trump is well-positioned to claim the 1,237 delegates he needs to win the nomination outright - even though that will require him to win 55% of the delegates that remain.

This may seem surprising. After all, Trump has won only 47% of the allocated delegates to date, so he'll need a larger fraction in the future than he's gotten in the past.

But Republican delegate-allocation rules are designed to help push a leading candidate like Trump over the top by awarding delegates more lopsidedly in the late contests than in the early ones.

In most of the primaries that happened to date, delegates have been allocated roughly proportionally - if you get 40% of the vote, for instance, you get about 40% of the delegates.

But going forward, the contests will give large bonuses to the winning candidate, meaning that Trump can do much better by getting about the share of the vote he's gotten to date.

Let's get into the numbers. So far, 1,472 Republican delegates have been awarded, and Trump has about 694 of them, give or take, according to estimates by Daniel Nichanian - we're still awaiting final results from Tuesday. There are 983 delegates left to award, and Trump will need 542 of them to win.

Of those 983 delegates remaining, 659 will be awarded in states whose delegate rules strongly favor the winner. That includes 217 delegates from six winner-take-all states, like Arizona and New Jersey.

Another 442 delegates will be awarded in seven states with some form of "winner-take-most" rules. In these contests, some fraction of the delegates goes to the statewide winner, while other delegates are awarded to the winner of each of the state's congressional districts. If you win the state and win every congressional district in the state, you get all the delegates. Remaining states with rules like this include California, Indiana, Pennsylvania, and Wisconsin.

For a preview of what's to come, look at Missouri, a winner-take-most state that voted on Tuesday. Trump appears to have won it by a tiny margin over Texas Sen. Ted Cruz. He led by about 1,726 votes out of 935,794 votes cast.

But Trump's win with 40.8% of the vote should be good enough for him to claim about 71% of Missouri's 52 delegates: 12 for winning the state, and 25 for winning five of the state's eight congressional districts. Cruz, who got 40.6% of the vote, will receive just 29% of the delegates.

Trump benefits from these rules partly because he's ahead - and partly because of how his support is distributed. Winner-take-most states award the same number of delegates in each congressional district, even if the district contains few Republicans.

In California's winner-take-most primary, for instance, the winner of Nancy Pelosi's San Francisco-based district will get the same number of delegates as the winner of a conservative district in the Central Valley. Trump tends to do especially well with Republicans who live in heavily Democratic areas, so even if he has a close loss in California, he could easily walk away with a majority of the district delegates by winning in areas that cast few votes.

You could see this effect in Illinois and Missouri. Trump won nearly all the delegates from heavily Democratic congressional districts in Chicago and St. Louis, while Cruz ran stronger in more Republican parts of the states.

Plus, Trump has one more advantage. Of the 250 delegates remaining to be awarded in states with some form of proportional-delegate allocation, 95 will be awarded in New York. But New York's rules are a hybrid somewhere between proportional and winner-take-most.

A candidate who gets more than 50% of the vote in a congressional district will get all three delegates from that district, and a candidate who gets more than 50% statewide will get all 14 of the delegates allocated statewide.

New York should be an extremely strong state for Trump. And he could end up with a lopsided majority of the state's delegates despite its technically proportional rules - by breaking 50% statewide, or at least in many heavily Democratic congressional districts.

So for Trump's purposes, you can think of 77% of the remaining delegates - 754 of them - as being awarded in states with rules that lopsidedly benefit the winner, be they winner-take-all, winner-take-most, or New York's unusual system.

Of course, Trump will also pick up a handful of delegates from remaining states with proportional allocation, like Rhode Island and Oregon.

If Trump continues to run as strongly as he has to date, those rules should be enough to get him the 542 additional delegates he needs to make him the nominee. To stop Trump, Cruz and Ohio Gov. John Kasich will have to significantly outperform their past showings. They will have to beat him in states like Arizona and Pennsylvania, even though they couldn't come close to beating him in Nevada or Michigan.

Cruz fans are hopeful about Arizona. Trump generally underperforms in the West, and Cruz has done well in states demographically similar to Arizona, with the exception of Nevada. But immigration is likely to be a strong issue for Trump in Arizona. If he takes the state's winner-take-all primary next Tuesday, it will be a clear sign that he is on the way to winning outright.