the only viable left leaning political party in the US?

I might be misunderstanding you, so I apologize if that is the case, but if you are referring to the Democrats they are far from left leaning. They aren’t even center leaning.

You can’t even say they have a better track record than the Republicans. They bomb countries as much (or in recent years even more) than the Republicans. They advocate for wars. They fund ICE even more than the Republicans. They stand up just as much for reproductive rights (read: not at all). They just do all of it while waving a rainbow flag.

I really hope you meant the Greens or the CPUSA; which have their own issues but are certainly more left than either the Democrats or Republicans.