Ted Cruz is weighing in on the Los Angeles mayoral race ... telling TMZ DC things are so bad in Los Angeles under Mayor Karen Bass ... while praising Spencer Pratt.

Jacob got the Senator from Texas on Capitol Hill and asked him if a potential Trump endorsement would help or hurt Spencer in a solid blue area.

Ted says he doesn't know what the result of Trump endorsement would be ... but he doesn't think it would matter either way, considering what he feels is a steep decline in the quality of life for Angelinos under Bass..

Spencer's been ripping Bass in political attack ads, and Ted says they're going viral because "they speak to a real truth" about "devastating" Bass policies when it comes to wildfires, crime, drug use in the streets and homelessness.

The way Ted sees it ... even the most liberal voter in Los Angeles doesn't want their kids to have to dodge homeless people on the way to school ... or step over human feces on the way to work.

No word if, or when, Spencer might pick up a Trump endorsement ... but it sounds like he's got one here from Ted.