With the departure of Jeb Bush from the Republican field and Marco Rubio’s top-tier finish in South Carolina, the path is now clear for Rubio to claim the establishment mantle, not because he is a particularly strong candidate but because he will be the last acceptable candidate standing after every other option fails. Rubio’s disastrous New Hampshire debate performance and his subsequent lackluster primary showing would have meant the end of his candidacy in a typical year. Instead, he was able to rally the support of the South Carolina Republican establishment because there was no other realistic place for them to turn.

A peculiar pattern started to develop last fall, as once-heralded prospects exited the stage while inexperienced candidates soared. Rick Perry, Scott Walker, Bobby Jindal – all governors of states with significant populations, all touted at one point as the future of the party – were out before the balloting began, while Donald Trump, Ben Carson and Carly Fiorina took turns dominating the conversation. Then Chris Christie fell after New Hampshire and Bush exited tonight. Kasich is finding little traction outside New Hampshire; when he leaves, a field once crowded with governors will have none. Who else is left as an alternative to Trump and Ted Cruz?

Choosing a candidate because he is the least worst choice is as problematic as selecting a candidate based on electability, because eventually the flaws that prevented that candidate from emerging on the merits will make themselves known. In the near-term, establishment Republicans will get the winnowing they were denied after New Hampshire, setting up a three-way race with a true believer (Cruz) and a mouthpiece for the angry and disaffected (Trump). This is a necessary but far from sufficient condition for preventing a Trump or Cruz nomination. Rubio remains vulnerable on immigration, the animating issue for a large portion of the Republican electorate, and he can look frightened and weak when attacked. At some point it will be helpful for him to actually win somewhere. And let’s not forget that Donald Trump won the New Hampshire and South Carolina primaries by double-digit margins. Let me say that again: Donald Trump won the New Hampshire and South Carolina primaries by double-digit margins. Had Rubio pulled this off, the calls for everyone else to withdraw would be deafening.

Three-way contests can be unpredictable, but after many inconclusive months the contours of the Republican race are starting to take shape. The real test of how well the Republican Party can endure its own nominating process will be what happens when the sizable but incompatible factions represented by these candidates have to come together in the end.