Lauren Conrad might not be fond of Spencer Pratt ... but he swears she'd vote for him if she saw the s****y conditions in Los Angeles!

Pratt responded to Conrad avoiding the question of whether she'd vote for him for mayor on "Today" -- she simply stated she's not a resident of L.A., without giving her opinion on his political aspirations -- by claiming she'd "vote for me if she lived in LA and her kids had to walk over fentanyl zombies and human poop on their way to school."

We're not so convinced ... Conrad gave Kristin Cavallari a hard stare after she said, "I will always have a soft spot for Spencer. I think he's great" -- and she also told hosts Jenna Bush Hager and Sheinelle Jones they were "asking me about people I haven’t spoken to in decades."

As you know ... Conrad, Pratt, and his wife, Heidi Montag, had a massive falling out in the early 2010s after Lauren accused Heidi of spreading a rumor about an alleged sex tape involving LC.

Pratt announced his mayoral run in January, one year after his home burned down in the Palisades Fire. He blames L.A. Mayor Karen Bass and others in the city government for the tragedy.

While he's gotten some support from fellow reality stars, other people -- including his own sister, Stephanie Pratt -- has urged people not to vote for him.