If the G.O.P. is going to survive as a decent and viable national party, it can’t cling to the fading orthodoxy Cruz represents. But it can’t shift to ugly Trumpian nationalism, either. It has to find a third alternative: limited but energetic use of government to expand mobility and widen openness and opportunity. That is what Kasich, Rubio, Paul Ryan and others are stumbling toward.

Amid all the vulgarity and pettiness, that is what is being fought over this month: going back to the past, veering into an ugly future, or finding a third way. This is something worth fighting for, worth burning the boats behind you for.

The hour is late and the odds may be long. But there is still hope. It’s a moment for audacity, not settling for Ted Cruz simply because he’s the Titanic you know.