TAKING CONTROL OF ONE OF THE POLITICAL PARTIES
This option has both pros and cons.
The advantage is that the organization and structure already exists, no need to start from scratch.
The disadvantage is that the politicians control the party. Even groups such as the Tea Party in the Republican Party would be against such a take-over.
Another disadvantage is all the special interest groups that support the party will be against the take-over.
Everyone currently involved in the party with fight to retain the status quo.
The above refers to both parties.