Liberalism right now is caught between Scylla and Charybdis of left- and right-totalitarianism and neither is clearly the lesser.
But this precarious position we find ourselves in is nothing new. I'd say that's been our lot since Day 1. Liberalism has survived by not indulging in the ruthlessness of the totalitarian philosophies. We have survived by avoiding the ruthlessness.
I say we do three things to strengthen liberalism:
Forge alliances with individuals where we can and on particular issues. Find the George Wills, the Sen. Sinemas, etc., and work with them where we can. It is true that our list of allies grows thin, but they are out there.
Emphasize the virtues of liberalism. Polling data show Americans are pissed at both parties to record degrees. They want a third way. We can offer that. Those of you who speak to the public need to emphasize the virtues of liberalism. When I write, I try to emphasize the Buchanan point that liberalism allows us to become a better version of ourselves and the Smithian/Hayekian point that liberalism allows us to discover the best ways to help each other. We must emphasize how liberalism is, ultimately, a social philosophy. Emphasize the empathy of Smith. It seems to me Americans are rejecting the self-centered nature of totalitarianism. We can provide an alternative.
Reject ruthlessness. When fighting monsters, one must beware not to become a monster themselves.
Perhaps it is a losing battle. Perhaps we will metaphorically fall on this battlefield, our bodies left to be picked apart by carrion crows. Perhaps, like Ozymandias, all that will remain is a plaque that states "look upon my works, ye mighty, and despair!" If that is what Fate has in store for us, so be it. But if history has taught us anything, it is this: liberalism is a hardy weed, not a delicate flower.