James Carville Compares Rep. Haley Stevens to 'Used Condom' Over GOP Endorsement

James Carville is catching major heat for comparing Rep. Haley Stevens to a "used condom" ... all because the Democrat crossed party lines to endorse a Republican in Michigan's heated Senate race.

The veteran Democratic strategist went off on Stevens during Sunday's episode of his Politicon podcast ... declaring her political career over after she backed Republican Mike Rogers instead of Democrat Abdul El-Sayed.

"If you think that these Republicans are going to treat you as anything other than what they view you as -- a used condom," Carville said ... adding, "The Democrats don't even think you're worth a used condom."

And he wasn't done ... telling Stevens, "You made your bed, sleep in it, you s*** in your mess kit, eat it."

The blowup comes after Stevens stunned Democrats Sunday by endorsing Rogers just two days before Election Day ... a dramatic reversal after previously supporting El-Sayed, who defeated her in the Democratic primary.

As TMZ previously reported ... Stevens' fiancé, Jason Turkish, joined "TMZ Live" Friday and warned she could withdraw her support unless El-Sayed condemned campaign ads she considered antisemitic.

Stevens ultimately made the switch after El-Sayed's campaign said she no longer felt welcome on his campaign trail ... while Democratic leaders blasted her decision to back the Republican nominee.

Carville even dragged Sen. John Fetterman into the mess ... suggesting he and Stevens should open a cheeseburger restaurant together.