Ted Cruz, we are told, has a fondness for American popular music. We therefore trust he knows by heart and can belt out on demand Frank Sinatra’s "New York, New York."

Start spreading the news, I'm leaving today. I want to be a part of it, New York, New York . . . If I can make it there, I'll make it anywhere. It's up to you, New York, New York.

Sing it, Ted!

And when you're finished singing, ignore the counsel of the fainthearted who suggest downplaying New York. It's true that Donald Trump will most likely win his home state. But you cannot avoid competing there, and you shouldn't want to avoid competing there. A decent performance in New York will set you up for doing even better the next week in states like Pennsylvania and Maryland, and then beyond.

For the fact is that Ted Cruz's path to the nomination runs through a surprisingly strong showing in New York, and the fact is that Trump is faltering. Trump, it's true, also stumbled at the very beginning of the campaign, in Iowa, but he was allowed to recover. A couple of days after he lost Iowa, we warned in this space that

he's far from politically dead and decisively defeated. Yet large parts of the Republican party and the conservative coalition remain as foolishly complacent as they were during his ascendancy. And some of the anti-Trump forces are now heaving sighs of relief and letting down their guard. .  .  . It's dispiriting that more of an effort isn't being made to decisively knock Trump down and out.

Trump wasn't knocked down and out after Iowa. Maybe he couldn't have been. In the event, he survived and flourished—for a couple of months. But now it seems the Republican party's flirtation, not to say infatuation, with Trump may have peaked. The true believers are still there. But they constitute less than 40 percent of the party. His more decent and thoughtful followers, as well as his more savvy and opportunistic enablers, are beginning gradually to abandon ship.

Where better to take a stand, to make the case against Trump, and to begin to move beyond Trump, than in New York? After all: Ted Cruz is a constitutional conservative. To whom were the Federalist Papers, the authoritative commentary on the Constitution, the greatest work of political thought produced in America, directed? "To the People of the State of New York." Who was one of the authors of those papers? Alexander Hamilton of New York.

Ted Cruz will be a busy man over the next ten days. But he could do worse than visit Hamilton's gravesite in Trinity Church Cemetery at the intersection of Broadway and Wall Street in New York. He could do worse than go a few miles uptown to watch the musical Hamilton—a tribute to the vitality of the American founding and American popular culture. He could even do worse than visit Hyde Park to pay his respects to Franklin Roosevelt—a problematic figure in many ways, but the man who saw us through a great war to defend Western civilization in the 20th century, which Cruz understands to remain under assault in the 21st.

Ted Cruz is an impressive politician with an important agenda. But the Cruz campaign is now about more than Ted Cruz. It is about whether a great political party can be saved from nominating someone with "talents for low intrigue, and the little arts of popularity" who is manifestly unfit for "the distinguished office of President of the United States" (Federalist 68). The Cruz campaign is about making the case for Cruz—but it's also about the crucial task of saving us from the seduction and the nightmare of Donald Trump.

It is also about whether other individuals of distinction, some of whom have toyed with Trump, will step up to help. Such men surely understand that "the republican principle .  .  . does not require an unqualified complaisance to every sudden breeze of passion, or to every transient impulse which the people may receive from the arts of men, who flatter their prejudices to betray their interests." Rather, "When occasions present themselves in which the interests of the people are at variance with their inclinations," such individuals surely know it is their duty "to withstand the temporary delusion, in order to give them time and opportunity for more cool and sedate reflection." They are surely aware that "Instances might be cited in which a conduct of this kind has saved the people from very fatal consequences of their own mistakes, and has procured lasting monuments of their gratitude to the men who had courage and magnanimity enough to serve them at the peril of their displeasure" (Federalist 71). It would be good to see some striking instances of conduct of this kind.

The Cruz campaign is, of course, also about whether Ted Cruz himself can rise to the challenge and the occasion. Can he now assume the leadership of not just a faction but the whole of the Republican party? Can he now speak not just for the conservative movement but for our Constitution and our country?

Ted Cruz has dreamed of being president since he was a young man. We will soon learn whether these were the pedestrian dreams of commonplace ambition or whether his ambition is a "love of fame, the ruling passion of the noblest minds." If so, his presidency could offer the hope of constitutional reinvigoration and national distinction. The path to that reinvigoration and distinction now runs, appropriately, through the great state of New York.