There is only one reason the NRA has influence: members and sympathizers will vote on thier recommendations, they have a lot of members and the NRA will always endorse the most sympathetic candidate to thier cause regardless of party affiliation.
The pro encryption lobby could emulate this. Lobby groups like the eff need more members and crucially need members to vote for who they recommend regardless of the candidates other views ie. vote for Trump if he said he was pro encryption.