The mass movement would be you, the people, actively putting pressure on the representatives. That is what you're accountable for. If it's not happening, it's because you're not doing it.
This would be called lobbying. It happens already. It just doesn't happen for the issues you care about. Again how can you change the LAWS, if haven't elected anyone willing to change them? There is a political procedure. You can join one of those independent orgs and help draft these demands too.
Just to be clear, the variation in elections comes during primaries. At the national level, there are no alternatives because the people don't support alternatives. So again, it's up to you, the people, to make the inclusion of alternatives a priority. Ask yourself this, you're upset because there are no alternatives, but has anyone in your own family actually cared to research alternative parties or voted for the conventional option?