The challenge is to make the US into a Multi-party system (e.g. at least Four-party at minimum) instead of the OTL's Two-party system, where other political parties manage to now and again reach power.
Aside Theodore Roosevelt's Progressive Party and Ross Perot standing as an independent that would likely depend on different PODs, what other OTL (pre/post-1900) defunct major/third political parties could have not only survived but also proved capable of occasionally winning US elections in place of the Republicans and Democrats?