A political party is not a manifesto, it's an organisation.
I actually think there's room for a party to start gaining ground in the US. There are so many elected offices that the surface area is huge. Great for "guerilla tactics." IE, earning easy victories by picking the battle..
Maybe your pick a thousand low key positions, and work on them. Standing a thousand candidates with success, even if the offices are minor, makes you a full fledged party by default.
Uncompetitive regional strongholds, are another opportunity. You could split the large party's vote and earn immediate relevance. You could even split the small party's vote and try to steal 2nd place. That might make you one half of a dichotomy the next time. You could run candidates in republican or democratic primaries. The primary electoral system is diverse, so you can choose to do this where it has a chance.
So, where's the party? Who's running? Where/what? Who else is involved?
A political manifesto is OK, I guess. A party manifesto... that would be a lot more interesting. What are you planning to do?