What are registration requirements for a new federal political party in USA?
The Federal Election Commission handles this at the federal level. According to their website, registration requirements include:
- The party should have nominated Presidential and Vice Presidential candidates in numerous states (as well as other candidates for other offices).
- Engaging in the normal activities of a party, such as voter registration drives.
- Holding a national convention and having national offices
Federal registration requires already being registered in "numerous states". Each state can have different requirements. For example, my state (Kansas) requires a petition to be filed with the Kansas Secretary of State. The petition must be signed by at least 2% of active voters (operationalized as the number of voters who voted in the last gubernatorial election).
I don't have a general knowledge of state requirements to register a party, but I quickly looked up Nebraska and Maine's requirements and they are similar (although they have different percentages required).