Your government is fundamentally different than ours. Given 2 large entrenched parties which are nearly equal in a system which is winner take all at every stage of the game any third party which gets any substantial portion of the vote splits the vote with whatever party it is most like ensuring its opposition wins.

EG imagine you wanted to grow say the green party in given district which is 51% Dem 49% Republican. If it were to wildly successful it would need to grow from 1% to a plurality organically probably over several or even many election seasons. It is unlikely to get many Republican votes because Republicans have solidarity and its positions are substantially different so by the time the green party has grown to 3% of the vote its throwing every election to the Republicans. This continues to be true at 30% because 90% of its votes come from the left. At some point you would reach changeover and become the defacto left wing party but by that time you will have found the state has gerrymandered your district to the point where you can’t win and all the money essentially millions of dollars in legal bribes is still flowing to the now minority party.

This is literally impossible to fix at the ballot box by people voting for third parties. This is why for example the green party has existed for 40 years and in all that time has never elected anyone to federal office and has in only a handful of cases held a state office wherein they run and stay green.

The US system is designed to make this impractical and it has only become more so with intensely parties making getting votes from both sides increasingly ridiculous. Anyone you would want to elect is going to have to take a stand against essentially the American nazi party in power now.