I know we’re supposed to say ‘of course Trump absolutely can’t be the Republican nominee but….” before we then point out his badness. Here’s the thing: he can be the nominee — because of Citizens United.

Let’s say he caps out at 30 percent. Just never gets above that. We’ve gotten used to the idea that the nominee is someone who wins a majority of the primary or caucus votes. For the past few decades it has played out that way because of a particular dynamic. As one or two candidates eventually emerge as the leaders, the other candidates drop out, in large part because it becomes impossible for them to raise enough money. When the field shrinks to a few people, thirty percent goes from being a big number to being a small number. Indeed, for all Jeb Bush’s problems I suspect that in a head-to-head matchup with Trump, he would be ahead.

But, if you have a pet billionaire, you can stay in much longer. So, you could have a situation where instead of one or two people remaining against Trump, you have four or five. The math might be: Trump 30, Bush 25, Cruz 15, Walker 15, Rubio 10, Other 5. Citizens United enables the third, fourth and fifth candidates to keep running and maintain a critical mass of support. One can easily imagine the candidate telling their sugar daddies, “Trump must and will be stopped. If we stay in, we’ll be positioned to step in!”

In a way, this is a throwback to an earlier time when fractional candidates could win the nomination. In 1972, George McGovern won the Democratic party nomination with a total of 25 percent of the primary votes, in part because several candidates were strong enough to remain appealing until the convention: Hubert Humphrey with 25 percent; George Wallace, 23 percent; and Ed Muskie, 12 percent.

In some of the state contests, the presence of several strong contenders ended up helping McGovern. For instance, he won the April 4th Wisconsin primary with 29.5 percent of the vote as Wallace got 22 percent, Humphrey go 21 percent, Muskie got 10 percent, Scoop Jackson got 7.8 percent and John Lindsay (!) got 6.7 percent. McGovern benefited from those other candidates maintaining strength deep into the primary season. Trump will, too.

Of course, there are many other reasons Trump might not be the Republican nominee. In his verve to not play by the rules he might forget to play by some of the necessary rules – like getting on state ballots or recruiting caucus delegates. While he could be capped at 30 percent, his floor could certainly fall out, though it’s a bit hard at this point to know what would knock him down. Perhaps if he reveals that he’s bankrupt, gay-married to Al Sharpton and an NPR donor?

So, I’m not saying it’s likely he’ll hit and remain at 30 percent but we do need to rid ourselves of the notion that someone with an upper cap on his support cannot win the nomination.

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Steven Waldman is chair of the Rebuild Local News Coalition, cofounder of Report for America, and a contributing editor at the Washington Monthly.