Exit and entrance poll data reported by CNN tells a different story. In nearly every state, Trump does as well or better among those who identify as Republicans as he does with independents.
Cruz is making excuses, but other Republicans are hoping to push Trump to the left in an effort to make him less appealing to primary voters. (Clearly it's not working.)
But of course Democrats don't want to claim Trump either. In fact, there appears to be some nervousness that Trump may appeal to Democrats in the general election, siphoning off support from the eventual Democratic nominee. Former Barack Obama adviser Dan Pfeiffer tweeted on Tuesday night that Democrats "would much rather face Cruz than Trump." When asked, Pfeiffer explained to me that he meant that the party's "electoral and demographic advantage is such that, to win, the Republicans need a candidate that can dramatically change the paradigm. Cruz is Romney with less appeal to independents, and Romney was drubbed electorally."
This argument makes intuitive sense. Trump's base of support has been largely less-educated, less-wealthy white voters, the sort of blue collar voters who have been drifting away from the Democratic Party for some time. We looked at the shift among white voters shortly before the 2014 election.
If Trump can pull those voters to the Republican side the way Ronald Reagan did in 1980, it could change the calculus of the race.
One problem is that Reagan and a few decades of other outreach already pulled away a lot of those voters. The General Social Survey tracks party identification over time, and among white voters with a high school education, they've already moved nearly 10 percentage points away from the Democrats since Reagan's election.
There are still some, of course. Last December, the Times dug into data suggesting that Trump's support was strongest among people who said that they were Republicans but who were actually registered as Democrats. That's not a big group, and it's a group that probably overlaps with the more-moderate electorate with which Trump has been doing well.
In the primaries so far, there's not much evidence that Trump has done particularly well in places where there's more support for Democrats. If he were so inspiring that Democrats wanted to come out in open primaries, it seems likely that he'd do better in areas where President Obama did better in 2012. He hasn't.
What's more, general election polling so far doesn't indicate that Trump would do any better with Democrats than Hillary Clinton would with Republicans.
It's hard to see the subset of white, lower-income voters in those polls, which typically don't dive that deep into the electorate. Clinton wins lower-income voters, but that may be in part because she also does well with nonwhite voters, a group that often overlaps with lower-income ones.
None of this is definitive. The story of the past nine months, after all, has been that the numbers we saw and interpreted didn't capture the rise of Trump in the Republican primary. He wasn't supposed to win, because the numbers said that he shouldn't. Trump's strengths weren't captured in those polls.
A general election electorate is necessarily different than the Republican primary electorate, so it again feels safe to assume that Trump's influence with Democrats may be smaller than he likes to claim. But this, too, goes back to Pfeiffer's point: Who knows?
What we thought we knew about politics on March 2, 2015, has been broken. And it was Trump himself who broke it.