It may have been the most important non-endorsement of 2016.  

Nebraska freshman Sen. Ben Sasse put into words on Facebook and Twitter what other Republican officeholders are muttering over late-night drinks — that he could not vote for Donald Trump in November, even if he were opposed by Hillary Clinton.  

Sasse’s gutsy move may help inspire other mainstream Republicans in Congress to draw their own moral lines in the sand. Mitt Romney has joined the Dump the Trump caucus with a tweet describing the bilious billionaire’s non-answer on the KKK as the “coddling of repugnant bigotry.”  

With Trump poised to sweep most — if not all — the Super Tuesday states, the level of depression in the rational wing of the Republican Party is becoming akin to the mood among stockbrokers in late 1929. But if more Republicans speak out about bolting the party if Trump heads the ticket, the entire calculus of the nomination fight changes.  

No longer would the question be: Can Marco Rubio come from behind to defeat Trump? Instead, the arithmetic would become: Can the party regulars stop Trump from winning the 1,237 delegates he needs in Cleveland?  

Under this scenario, there would be no more talk of winnowing the field so that Rubio can take on Trump one-to-one. Instead, the goal would be to keep as many delegates as possible out of Trump’s short fingers. In the near term, it would be why John Kasich should be encouraged — rather than scorned — for making a stand in winner-take-all Ohio on March 15.  

And if Kasich and Rubio in Florida fail to thump Trump on the 15th, then there would be a strong argument for a late entry by a prominent Republican to run in the June primaries. This would not necessarily be a route to the nomination, but instead part of a crusade to save the Republican Party from a moral rout.  

Maybe Romney or Paul Ryan could enter the California primary (filing deadline: March 26) or take on the sputtering carcass of Chris Christie’s deflated ego in New Jersey (filing deadline: April 4).  

We have gotten out of the habit of thinking of a nomination fight as a battle to the convention floor. The last time that candidates refused to fold a losing hand was in San Francisco in 1984 where Gary Hart and Jesse Jackson opposed de facto nominee Walter Mondale to the bitter end. In sharp contrast, Hillary Clinton was only 104 delegates behind Barack Obama when she bowed out after the June primaries in 2008.  

The 1980 Democratic convention in New York (pitting incumbent President Jimmy Carter against the-dream-shall-never-die candidacy of Ted Kennedy) may provide the most relevant model for anti-Trump Republicans.  

Like the Republicans today, Democratic delegates in New York were bound to their candidate for the first ballot. But badly trailing in the delegates, even as Carter’s approval rate hit 21 percent in the Gallup Poll, the Kennedy backers came up with a last-ditch strategy.  

Their clever idea was to free the delegates to vote their conscience instead of being robots forced to obey the results of the primaries or caucuses that selected them. Overturning the Robot Rule would have been possible, in theory, because conventions as a body have the power to change the rules — and delegates are always free agents on procedural votes.  

The gambit didn’t work for Kennedy because nostalgia for Camelot was not strong enough a motivation to prompt many delegates to rebel against an incumbent president.  

But the stakes in Cleveland in July would be infinitely greater — with the threat of the first takeover of a modern political party by an authoritarian who traffics in racism and exudes contempt for the First Amendment. Under these circumstances, there would be nothing anti-democratic about GOP leaders using every mechanism in their power to stop Trump. Gaming the rules, after all, is what Ronald Reagan tried against Jerry Ford in 1976.  

It is worth remembering that — even with a delegate lead or a majority — Trump would face built-in disadvantages in Cleveland. Paul Ryan would be the convention chair and other GOP insiders would probably control relevant committees like convention rules and party platform. In some states, Trump does not get to pick his delegates slates, but instead is saddled with party stalwarts of dubious loyalty.  

The political press corps is wedded to the doctrine of Premature Certainty — and tomorrow night many TV pundits will probably predict that the GOP race is all but over. But such glib forecasts ignore how many hurdles — thank God — still stand between Trump and triumph.  

The recent attacks on Trump by Rubio combined with the incendiary comments on the Klan may gradually bring down his poll numbers as Republicans realize the real-world consequences of a protest vote. Losing winner-take-all states such as Florida and Ohio may also dent Trump’s aura of inevitability.  

There is also the question of whether Trump can finally figure out a way to go too far even by the forgive-all standards of his voters. Having embraced Vladimir Putin and Chinese tactics in Tiananmen Square, maybe Trump will take the next step and express his admiration, while campaigning in Florida, for the tough-guy record of Fidel Castro.  

Sasse and Romney represent a wing of the Republican Party that will not surrender its traditions and its honor without a fight to the convention floor — and beyond. Viewed in those terms, the Super Tuesday primaries represent the end of the beginning rather than the beginning of the end.  

Roll Call columnist Walter Shapiro is covering his 10th presidential race. A fellow at the Brennan Center at NYU, he is lecturer in political science at Yale and is the author of the forthcoming in June ‘Hustling Hitler: The Jewish Vaudevillian Who Fooled the Fuhrer.’ Follow him on Twitter at @MrWalterShapiro .  

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