Tuesday night went about as well as possible for Donald Trump.

Two weeks ago, after a rough stretch of states for Trump, we issued a series of delegate projections that included something called a “path-to-1,237” projection, a set of targets that would allow Trump to clinch a delegate majority without having to rely on uncommitted delegates. With Trump’s terrific results in New York last week and even better ones in the five states that voted on Tuesday, Trump is running a little ahead of that path.

Based on provisional results, it looks as though Trump will sweep every pledged delegate in Maryland (as a result of winning every congressional district), Connecticut (as a result of winning every congressional district and getting more than 50 percent of the vote statewide), Pennsylvania (where statewide delegates are awarded winner-take-all) and Delaware (ditto), along with 11 of 19 delegates in Rhode Island (which is highly proportional). Combined with the New York results, that gives Trump 200 delegates since we issued the path-to-1,237 projections, five delegates ahead of his original targets.

STATE PATH-TO-1,237 PROJECTION ACTUAL TRUMP DELEGATES Wyoming 1 0 New York 91 90 Maryland 32 38 Connecticut 28 28 Pennsylvania 17 17 Delaware 16 16 Rhode Island 10 11 Total 195 200 Trump’s back on a potential path to victory Sources: The Green Papers, Elections.MARYLAND.GOV

None of this was assured, or necessarily all that likely, when we surveyed the race a few weeks ago. Trump was coming off one of his worst results of the campaign in the Wisconsin primary, along with a disastrous series of results in state and local Republican delegate-selection conventions (those will still hurt him if the Republican convention goes to multiple ballots). While the Northeast had long appeared to be a reasonably strong region for Trump, the polls two weeks ago suggested it was a tossup whether he’d get to 50 percent of the vote in Connecticut; instead he won it easily with 58 percent of the vote. It looked as though he’d probably lose a couple of congressional districts in the Washington suburbs in Maryland even if he won the state; instead, he swept all eight districts.

In other words, something changed for the better for Trump in the past couple of weeks. At the time we issued those delegate projections, Trump had yet to get 50 percent of the vote in any state and both his national polls and statewide results seemed stagnant. Now he’s gotten over 50 percent in six states in a row. Whereas Trump had once been a safe bet to underperform or, at best, match his polling averages, he’s now beaten them in the last six states.

Having moved to a demographically favorable bloc of states is part of the equation, but not all of it. Compare Trump’s excellent result in Maryland (55 percent of the statewide vote) to his mediocre one in demographically similar Virginia on Super Tuesday (35 percent). Pennsylvania, where Trump got 57 percent of the vote on Tuesday, isn’t all that different from Illinois, where he got 39 percent on March 15. (The Pennsylvania result is especially important given that Trump also got favorable-seeming results among the 54 officially uncommitted delegates elected in the state on Tuesday night, which will give him a cushion if he falls a bit short of 1,237 pledged delegates.)

The question is what’s changed for Trump, whether the change is permanent or temporary, and what implications it has for the next set of states to vote. More particularly: What it means for Indiana, which votes next week and awards its delegates winner-take-all (some statewide and some by congressional district), and which the path-to-1,237 projections had Trump winning. As much good work as Trump has done over the past two weeks, a loss in Indiana would mostly undo it.

One theory, which I proposed last weekend, is that Trump is benefiting from Republicans who buy his argument that the delegate system is “rigged” against him — or if you prefer the milder version, that the candidate with the plurality of delegates and votes should become the nominee. It’s hard to prove definitively that this is what’s behind Trump’s gains, but there’s some good circumstantial evidence for it. Polls suggest that Republican voters mostly take Trump’s side on the question of the nominee’s legitimacy, and the timing of Trump’s gains in the polls lines up well with when he started pressing the argument.

My original idea was that this sentiment might be moving undecided voters toward Trump — Republicans who just wanted to get the race over with and who didn’t want to go through the ordeal of a contested convention. After seeing the exit polls on Tuesday, however, I’d propose a slightly different version. According to the exit polls, Trump did not perform especially well among late-deciding voters — no better than John Kasich did. But recent turnout has been low as compared with earlier states. Whereas 25.6 percent of the voting-eligible population cast a Republican ballot in Wisconsin, according to Michael McDonald’s estimates, an average of only 9.9 percent of eligible voters have in the six northeastern states to vote over the past eight days.

STATE TURNOUT AS SHARE OF VOTING-ELIGIBLE POPULATION New Hampshire 27.8% Wisconsin 25.6 Alabama 23.9 Ohio 22.3 Missouri 20.7 South Carolina 20.3 Idaho 19.7 Arkansas 19.2 Mississippi 19.1 Georgia 18.8 Michigan 17.8 Tennessee 17.6 Virginia 17.0 Oklahoma 16.5 Texas 16.4 Florida 16.3 North Carolina 15.8 Pennsylvania 15.8 Illinois 15.3 Massachusetts 12.8 Vermont 12.5 Arizona 11.4 Maryland 10.6 Delaware 10.0 Louisiana 8.9 Connecticut 8.7 Rhode Island 7.8 New York 6.4 GOP turnout has been low in recent primaries Turnout estimates for states with incomplete reporting are extrapolated based on results as of midnight on April 27. Sources: Electproject.org, New York Times

So it may not be that undecided voters are gravitating to Trump so much as anti-Trump Republicans are discouraged. Trump faces unusually high levels of intraparty opposition for a front-runner — or at least he had seemed to until the past two weeks. But Kasich and Ted Cruz are also deeply flawed, and somewhat factional, candidates. It’s asking a lot of voters to cast a tactical vote against Trump when that tactic requires (i) going to a contested convention in order to (ii) deny the candidate with the plurality of votes and delegates the nomination in order to (iii) give the nomination to a candidate they don’t particularly like anyway. The #NeverTrump voters might not be voting for Trump, but they might be staying at home.

I mostly buy this argument — I’m as optimistic about Trump’s chances as at any point in the election cycle. (Granted, that isn’t saying that much given that I spent much of last year being highly skeptical of Trump’s chances.)

But I still have a couple of points of caution.

One is that it isn’t uncommon for candidates to run up the score in primaries that appear to be noncompetitive. In fact, this happens all the time. Polls usually call the winners right in primaries, but they often lowball their margins of victory. It isn’t very motivating to turn out for a guy who’s going to lose a state by 30 percentage points, even if doing so might win him an extra delegate under some obscure provision of the delegate rules. In Indiana, a genuinely competitive, winner-take-all race where Cruz is (theoretically) the clear alternative to Trump, that won’t be such a problem.

The other caveat is that the Republican race has not only defied “momentum” but often contradicted it. Whenever Trump seemed to be on a glide path to the nomination (such as after Super Tuesday or March 15), he’s had a setback. When he’s seemed to be vulnerable (such as after losing Iowa or Wisconsin), he’s rebounded.

This maybe — or probably — is just our reading too much into noisy data. But it’s possible there’s some sort of thermostatic effect at work. When Trump seems to be on the verge of becoming the presumptive nominee, there’s more focus on his awful general election numbers; meanwhile, the media’s incentives for covering him change, with the possibility of Trump imploding at a contested convention becoming a more attractive story than the man-bites-dog narrative of Trump winning the nomination in the first place. When Trump seems to be in trouble, conversely, Republicans are forced to contemplate the problems of a contested convention and the inadequacies of Cruz and Kasich, and the media becomes more eager to tell a Trump comeback or pivot story.

Indiana is important not only because of its delegates, but also because it will give us an indication as to whether the apparent change in Republican attitudes is temporary or permanent. If Trump wins Indiana despite its middling-to-fair (from his standpoint) demographics, he won’t quite be the presumptive nominee because he’ll still need to follow through with a decent performance in California. But he’ll at least be in the liminal zone that Hillary Clinton spent a lot of time in, with the race not quite wrapped up mathematically but close enough that something (a gaffe, a scandal) would have to intervene to deny him the nomination. Incidentally, Trump’s potential support from the uncommitted delegates in Pennsylvania will give him more margin of error in that situation.

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If Trump loses Indiana, however, that will suggest the race is still fairly volatile week-to-week, that he’s very likely to lose states such as Nebraska that vote later in May, and that the geographic and demographic divergences in the GOP haven’t reversed themselves so much as they’ve become more exaggerated. It will improve the morale of anti-Trump voters and change the tone of press coverage. And mathematically, it will make it hard (although not quite impossible) for Trump to win 1,237 delegates outright; he’d be back to fighting tooth-and-nail for every uncommitted delegate.

I don’t know what’s going to happen in Indiana. But Trump’s strong results over the past two weeks have changed the Hoosier State from potentially being “must-win” for Trump to probably being “must-win” for his opponents.