The political system is completely fucked. Going grassroots with direct action is currently the best way to both resist, and build horizontal decentralized power that isn't prone to the corruption and lobbying that the democrats have fallen to.
We can effect things drastically with a general strike. This targets the establishment's income streams, and can bring a fascist government to its knees if done on a large enough scale.
Contact a union and attempt to unionize your workplace so that the general strike is even more effective (plus, ya know, better pay and working conditions as a bonus!)
This method would not only work in the US, but anywhere in the world.
Continuing to participate in publicly visible resistance demonstrations like 50501 (the next one is July 17th) to encourage others to stand up with you and prove to that there are millions of others who will join them in the fight. A large part of Nazi Germany's success in taking over the country was a lack of massive public demonstrations against the new regime, making people feel helpless and afraid to take a stand.