Maybe the Pirate Party could organise themselves around being factions in the Democratic and Republican parties, trying to ensure those parties elect Pirate-friendly candidates.
Both parties have strong top down control over their respective primaries. Both in terms of direct influence and manipulation. For the Democrats you could observe this during Bernie's campaign for president. For republicans you could see it during Ron Paul's. Both had the majority in the primaries in terms of popular support but primary regulations were such that it didn't matter. Local and state factions were just overruled.
Neither one of those candidates had anywhere near majority support. The Democratic party made some changes since 2016 to make it harder for a Bernie-like candidate to be elected, but will still allow for any candidate with a majority of primary votes to be selected over the party's direct influence.
Neither of those candidates had majority support, especially Ron Paul. This is delusional.
I don't think any pirate party really had the numbers to make that happen. Usually a faction represents some larger group of people. The only way I see that happening is by unionizing tech. But that would be incredibly hard exactly because it would create a political force.