Moreover, the difficulty of Rubio’s task in a two-man race would be compounded by two things: One, he hasn’t yet shown he can go toe-to-toe with Trump, as each has avoided the other. Two, Trump and Rubio represent something close to the party’s two poles on the important issue of immigration, and the center of the party is likely nearer to Trump.

Some supporters of a loose immigration policy viewed the results of the South Carolina exit polling—which found that 53 percent of Republican voters would give illegal-immigrant workers a path to legal status, while 44 percent would deport them—as suggesting that most Republicans are with them on this issue. In truth, those results showed the opposite and made Rubio’s challenge appear all the more daunting.

First off, the question asked only about illegal immigrants who are working in the U.S., not illegal immigrants generally. Second, the 53 percent didn’t want to grant them eventual citizenship, which is Rubio’s position, but rather “a chance to apply for legal status.” Third, the answer most people would presumably prefer to give for illegal immigrants who are working—leave them alone but don’t give them legal status—wasn’t even provided. Fourth, when given a choice between making them legal or booting them out of the country, almost as many people said they’d send them packing as would let them stay. That does not bode well for Rubio.

Indeed, the prospect of having the candidate who is most like Chris Christie in manner take dead aim at Rubio for his wildly unpopular (among GOP voters) efforts on this issue should not make the Republican establishment feel confident of victory.