The filing deadline for Los Angeles mayor closed at noon last Saturday.

And this race looks nothing like the cakewalk Karen Bass expected.

Billionaire developer Rick Caruso passed on a rematch. LA County Supervisor Lindsey Horvath decided not to jump in. Former LA Times publisher Austin Beutner entered — then withdrew after the tragic death of his daughter.

A head-to-head contest against a Republican — even a celebrity outsider like former reality TV star Spencer Pratt — could become a referendum on Donald Trump in deep-blue LA. That’s a race Bass almost certainly would welcome.

Instead, she also drew a serious challenger from her left, in City Council member Nithya Raman.

Who even thought that was possible?

Raman’s entry turns the primary into a progressive purity contest. That’s the nightmare scenario for a Democratic incumbent — not a fight with the right, but a revolt from the left.

And it’s happening for a reason. Bass isn’t being challenged from the left because she’s too moderate. She’s being challenged because the city she runs isn’t working.

And let’s be clear: Bass isn’t exactly a centrist.

A close ally of Nancy Pelosi during her years in Congress, she built a reputation as one of the House’s more reliably liberal members. She........

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