The obvious choice in Tuesday’s special election for public advocate is Queens City Councilman Eric Ulrich, running on the Common Sense line.

Whoever comes out on top in a crowded field will fill the job until voters “get” to choose again in November. With the officially nonpartisan field packed with left-wingers, Ulrich has a shot, even though he belongs to New York City’s small Republican minority.

That status also makes him the best for a job that, as pretty much all the candidates seem to agree, should entail trying to make Mayor Bill de Blasio do a better job.

Especially when the other leading candidates all vow to be even more “progressive” than the mayor.

For that matter, the advocate becomes mayor if the incumbent for some reason exits before his term ends. And Ulrich’s main rivals include a proud apologist for terrorism and a dedicated cop-basher, either of whom would actually make us miss de Blasio.

As we’ve noted repeatedly, the Public Advocate’s Office doesn’t have a ton of power. (This election is actually costing the taxpayers at least seven times the office’s yearly budget.) At best, the job involves flagging City Hall’s failures on whatever issues the advocate chooses.

In that light, it matters that Ulrich chose “common sense” as his line, because he’s a voice for sanity: He wanted the Amazon deal to work; he’s worried about quality of life in a city whose police are under constant political attack; he’s a big supporter of charter schools and any alternatives that can offer parents and children new hopes for a solid education.

Our one major disagreement with him is over the handful of yeshivas that continue to resist city and state efforts to ensure that they teach the basic English and math skills required by state law. But it’s hard to see how he’d use this post to do any harm there.

Finally: This election offers the chance to send a message in a town where most politicians have been lurching left ever since Alexandria Ocasio-Cortez beat Rep. Joe Crowley in a low-turnout primary last year.

If you want a return to pragmatic moderation in city government, or if you just want city Democrats to stop embracing craziness, you should go out and cast a vote for Eric Ulrich.