Ridiculous. In America we don’t elect grossly underqualified C-list TV stars to high office. Especially not ones from New York.

The bright side: Of the four leads on “Sex and the City,” Miranda was clearly the smartest and most sober. Imagine Governor Carrie Bradshaw.

Her platform is, quite literally, to make the trains run on time.

Why should you care? Mainly for the sheer sporting fun of watching the left brutalize a liberal incumbent for being not quite left enough. (The right-wing version of that is less fun.) Nixon’s running as a Bernie-style progressive, capitalizing on the left’s annoyance with Cuomo for governing as more of a centrist in his first term as governor. He knows the ideological winds have changed within the party, though, and he has a powerful enemy in the form of NYC Mayor Bill de Blasio, another left-winger. Cynthia Nixon is a de Blasio buddy and is staffing up with some of his own campaign deputies for this primary challenge. She’s going to rip Cuomo for failing in more ideological ways — poor public schools, growing income inequality — and in less ideological ones, like failing to get NYC’s erratic subway service back on track.

Interestingly, Cuomo seems a little nervous about it. He’s been tacking leftward over the past few years to pander to New York’s Berniebros ahead of this year’s reelection bid but evidently feels insecure enough about his current position that he felt obliged to take a shot at Nixon’s C-list status in a conference call two weeks ago.

Mr. Cuomo also mocked Ms. Nixon’s celebrity status. She is best known for her role in the hit “Sex and the City” franchise, though she has also won Tony, Emmy and Grammy Awards for her work.

“Normally name recognition is relevant when it has some connection to the endeavor,” Cuomo said in the call. “But if it’s just about name recognition, then I’m hoping that Brad Pitt and Angelina Jolie and Billy Joel don’t get into the race because if it’s just about name recognition, that would really be a problem.”

What’s he so nervous about? Well, one of his former top aides just got convicted for corruption, a bad start to primary season. He’s also a 2020 hopeful, which raises the stakes for his gubernatorial race. He doesn’t just want to win, he wants to romp in the primary and general to show Democrats nationally that he’s a top-tier contender for the nomination. If Nixon overperforms with de Blasio’s help, it’ll give him a black eye even if he ends up being reelected. And the left finds him sufficiently impure ideologically that they could potentially mobilize for Nixon, if only to use the spotlight of the New York race to flex their muscles. A new NYT poll shows him leading Nixon 66/19 but that was before she declared her candidacy today and before big-name progressives like de Blasio have started swinging for her. Twenty percent’s not a bad place to start against an incumbent with universal name recognition and national aspirations.

That’s the other reason you should find this interesting: Cuomo could have his presidential hopes badly damaged if the “Sex and the City” insurgency does better than anyone expects. The higher Nixon goes, the weaker Cuomo’s “electability” argument gets — and potentially the stronger the national argument for nominating a progressive grows. The left has spent 15 months insisting that Bernie would have won in 2016 if nominated. If Nixon dramatically overperforms, if progressive candidates elsewhere do well this fall, that’s bound to affect the calculations of Dem primary voters in 2020 about who can and can’t win.