Our current electoral system is inherently biased against 3rd parties.
That’s true until it isn’t. Year-over-year, the nation can only support two parties nationally and one dominant party state-by-state. But which party (and which coalition of leaders) hold power can change in wave years, particularly when strong third party campaigns force rival parties to cater to the independent vote to get over the 50% hump.
There’s a podcast called Hell of Presidents that does a great job of documenting the rise and fall of state party organs and their impact on the national scene. The rapid collapse of the Federalists, the rise of the Jacksonian Democrats, the collapse of the Whigs and emergence of the Republicans, the rise and fall of democratic socialists, and the emergence of liberal progressives, movement conservatives, libertarians, and neoliberal democrats all begin with third party bids in small states.
While we don’t have more than two distinct parties in the US, we absolutely do have factions within the main two parties that have regionalized and polarized constituencies that are fighting for control of the national party apparatuses. Even setting aside guys like Trump and Sanders, just check out Nebraska’s Indie dark horse contender Dan Osborn, whose union organizing is putting him ahead of both party candidates.