If the Republican Party is to be saved from Donald Trump, Ted Cruz’s runaway victory in Wisconsin will have been the inflection point.

If you thought this service to the GOP would be met with plaudits from the party’s insiders, you obviously don’t know anything about their relationship to the Texas senator.

St. Augustine famously prayed, Dear Lord, make me chaste — but not yet. The GOP establishment’s prayer is, Dear Lord, deliver us from Donald Trump — but not with Ted Cruz.

The increasing likelihood of a contested convention in Cleveland has led to chatter about such a conclave turning to a white knight who has the advantage of being neither Trump nor Cruz. House Speaker Paul Ryan, who ascended to the third-highest constitutional office while (sincerely) saying he didn’t want it, is most often mentioned for the honor of winning a nomination he didn’t run for.

The white-knight talk has all the hallmarks of a psychological mechanism for GOP insiders to avoid acknowledging their dependence on Cruz, who is all that is standing between the party and what might be an epic Trump-led meltdown.

A convention could — and should — deny Trump the nomination, but it won’t be easy. There will be a perceived legitimacy problem in denying the top prize to the top vote-getter. This would obviously be magnified if a convention disregards both the first- and second-place finishers.

And for what? Electability? The only meaningful road test for a presidential candidate is running for president. Cruz has proved adept at it. He correctly read the mood of the Republican electorate and adjusted to Trump more skillfully than anyone else (not without some cringe-inducing moments).

It’s not clear what white knight would be any better. If Ryan had run this year, in all likelihood he would have gotten chewed up and spat out like anyone else associated with the establishment. Who else? Mitt Romney? He had his chance. A governor? The plausible ones already ran. A senator? Ditto. A general? They are always better in theory unless they are named Eisenhower or Grant.

Commentators skeptical of Cruz’s chances at a convention revert to the cliche that he is hated. It is true that people in Washington tend to loathe him, but a convention wouldn’t be a Senate Republican policy lunch. It would be stocked with Republican activists from around the country who have no firsthand knowledge of what Cruz did to so irk his colleagues, and probably don’t care.

All that said, it is possible to imagine a white-knight scenario, but only in a convention deadlock that might descend to South Korean-parliament levels of ugliness. The best, cleanest non-Trump scenario is that Cruz has the strength to win on an early ballot, and his anti-establishment credentials — and his tacking Trump’s way on immigration and trade — make a revolt by the Trump forces less potent.

In short, the only reasonable alternative to Trump is Cruz. This is the conclusion that Scott Walker and other conservative leaders in Wisconsin came to, and they backed Cruz to the hilt. Republicans around the country who care about the integrity of their party and its electoral chances should do the same.

Of course, Cruz will need to grow and adapt as a candidate. There were the first signs of that in Wisconsin, where he won the “somewhat conservative” vote and excelled in the suburbs. He would be an underdog against Hillary Clinton, but the man with the biggest media megaphone on the planet has been calling him a liar and a Canadian for months, and he trails Clinton by only 3 points in the RealClearPolitics average.

Trump and Cruz have both won states around the country and millions of votes, and engendered intense followings. There is no getting around that they are the choice confronting the party. It’s time to put away childish things, and pick sides.

Rich Lowry can be reached via e-mail: comments.lowry@nationalreview.com.