A contested Republican convention – the first in 40 years – may well be where the GOP race ends up; this is the first time since 1976 that genuine uncertainty has endured this deep into the presidential election process. But there’s one aspect that’s gone unnoticed and could silence the open convention chatter: Donald Trump may have an ace in the hole with Pennsylvania’s unbound delegates that could lift him past that magic delegate number of 1,237 by the end of the primary season.

Trump has had a tough few weeks, suffering a lopsided loss in Wisconsin and finding himself embarrassingly out-organized in Colorado. Still, he leads the Republican pack with 756 delegates, with Sen. Ted Cruz sitting in second with 545 and Gov. John Kasich and Sen. Marco Rubio (who by suspending his campaign retained many of his delegates) far back. And there’s more good news: The next six GOP contests will be staged on decidedly Trump-friendly turf. He’ll be the heavy favorite in all of them, starting in New York next week.

It wouldn’t be unreasonable for Trump’s share of the delegates in these contests to look something like this:

New York (4/19, 95 delegates): 85

Pennsylvania (4/26, 17 delegates*): 17

Maryland (4/26, 38 delegates): 32

Delaware (4/26, 16 delegates): 16

Connecticut (4/26, 28 delegates): 20

Rhode Island (4/26, 19 delegates): 10

The asterisk you see there represents Trump’s potential ace in the hole – more on that later. But for now, this would bring his delegate total to 936 heading into May. Things would get trickier then, with Indiana next up on May 3. There are arguments for why Cruz should win it and why Trump will. Given the state’s delegate distribution rules, the difference of just a few points could be huge. With a narrow win, Trump would be poised to gain at least 42 of Indiana’s 57 delegates. With a narrow loss, he could be in the single digits. This makes Indiana a real wild card in Trump’s quest for 1,237.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

The rest of May is a little more formulaic. Trump is expected to clean up in West Virginia and is a nominal favorite in Washington and Oregon, where the delegates are given out proportionally (meaning there won’t be the kind of wild swing that’s possible in Indiana). Nebraska is a winner-take-all state that seems tailor-made for Cruz. Let’s say Trump loses Indiana narrowly – a very big if – but that he wins three of the state’s congressional districts. That would make his delegate tally for May look something like this:

Indiana (5/3, 57 delegates): 9

West Virginia (5/10, 34 delegates): 30

Nebraska (5/10, 36 delegates): 0

Oregon (5/17, 28 delegates): 14

Washington (5/24, 44 delegates): 20

That would push Trump’s number to 1,009 – more than 200 shy of the magic number. And that would leave one last day of primaries, on June 7. But there are two giant states voting that day, winner-take-all New Jersey, where Trump will be strongly favored, and California. The Golden State is a particularly tough read. Trump leads polling in the state, but Cruz is within striking distance. More to the point, there’s the way the state awards delegates – three to the winner of each of its 53 congressional districts (plus 13 to the statewide winner). There are some indications that Cruz’s support may be distributed in a more advantageous way, but it’s very tough to tell, especially considering that many districts around Los Angeles and San Francisco are overwhelmingly Democratic and contain few Republican voters.

So for the purpose of this exercise, let’s say Trump wins California and takes the majority of delegates. Here’s what June 7 could look like for him:

New Jersey (6/7, 51 delegates): 51

South Dakota (6/7, 29 delegates): 0

Montana (6/7, 27 delegates): 0

New Mexico (6/7, 24 delegates): 12

California (6/7, 172 delegates): 121

That would leave Trump with 1,193 delegates – 44 short of the magic number. And if he’s short of the magic number, then we’re headed for an open convention. But not so fast, because this is where the asterisk from above comes into play.

At issue is Pennsylvania, which votes on April 26. Officially, only 17 delegates are directly at stake in that contest. They will go to the winner of the primary statewide. The other 54 are unbound delegates. They will run under their own names on the ballot, and if they are selected as delegates they will be free agents in Cleveland, free to vote for any candidate they want. Because Cruz has done well with unbound delegates in other states (like Colorado and North Dakota, where there was a premium on organizing), many are assuming that Pennsylvania’s unbound delegate bloc will be a problem area for Trump. It actually could be a major source of strength for him.

Here’s what we know. 162 Republicans are running for the 54 unbound slots in Pennsylvania, and 127 of them – so far – have replied to a survey from the Pittsburgh Tribune review. More than half of them are now saying that if elected as delegates they will simply vote for the candidate who wins their district. Another 20 say they’ll vote for Trump and 13 more say they are uncommitted (with several of them indicating that the results in their district will factor into their decision). Only 20 unbound delegate candidates in Pennsylvania now say they’d back Cruz, and only one is leaning toward Kasich.

Then there’s this: A new poll shows Trump winning Pennsylvania overwhelmingly, 48 percent, to 22 for Kasich and 20 for Cruz. If that holds, then the pressure to keep their word will be intense on those unbound delegates who are now pledging to honor the will of the voters. True, they could technically change their minds and join a movement to stop Trump anyway. But remember, many of these delegate candidates are party leaders who will have to deal with their district’s Republican voters long after this primary is over. If they are now pledging to honor the will of those voters and those voters then turn around and back Trump by a wide margin, there’d be serious blowback potential for any delegate who then reneges on a vow to honor the results in his or her district.

Under the scenario outlined above, Trump would finish the primary season 44 delegates short of the magic number. But that doesn’t count ’s 54 unbound delegates, and Trump – at least right now – is well-positioned to gobble up the lion’s share of them. That could be just enough to put him over the top and avoid a contested convention.