In an article titled “Why Brussels Makes an Anti-Trump Third-Party Bid Necessary,” Brian Beutler explains to the liberal readership of The New Republic magazine that another terror attack during a general election race between Hillary Clinton and Donald Trump could lead to a Trump victory. The only sure way to prevent this scenario, he argues, is for the #NeverTrump Republicans to launch a third party run against Trump – even though that will ultimately lead to a Hillary Clinton presidency.

The fear that animates #NeverTrump conservatives, like the fear driving some liberal voters to vote for non-Trump Republicans in open primaries, is that as the Republican nominee, Donald Trump could become president of the United States almost by accident.

As the Washington Post’s Greg Sargent has noticed, it isn’t uncommon for commentators to note with great foreboding—after violent incidents in Paris, San Bernardino, and now Brussels—that with Trump as the GOP nominee, we’d be one terrorist attack away from a Trump presidency.

It is this general fear—not of a terrorist attack, per se, but of how such an attack could lead to Trump becoming president—that has divided the right between those who want to stop Trump from securing the nomination by any means necessary, those who want to create some kind of third-party option for anti-Trump conservatives, and those who hope Trump can be controlled.

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One unknown variable in this formula is that past exogenous shocks served not just to harm incumbents, but to rally opposition parties. We don’t know what happens when the opposition is led by someone who lacks support from a significant faction of his own party. And this is where the immensity of the #NeverTrump burden comes into clear focus. If a similar shock were to hit our system later this year, in a head-to-head Clinton-Trump race, the anti-Trump right would have to turn a final corner and, in an ultimate indignity, become active Clinton supporters.

Committed #NeverTrump activists must realize there is effectively little difference between opposing Trump and supporting Clinton. But under normal circumstances, opposing Trump is as far as they’d ever need to go. In the event of a close contest, even one that narrows due to events outside either candidates’ control, they will need an outlet.

A third-party protest candidacy provides an escape hatch. Without that option, partisan instincts are much likelier to take over, and bring even the most committed #NeverTrump activists along for the ride.