The Federal Election Commission recognizes 8 parties as national committees.
The FEC has no mechanism to de-list a party that has gone defunct. The Natural Law Party is defunct, except it is still on the ballot and active in Michigan.
Previous Post from Richard Winger:
PhiBetaIota: If we all come together, we can force Congress to pass a law that mandates all eight parties appearing on all state ballots for all federal offices. We can do this in time for November 2012. This is the “one thing” we can all come together on, and it would then impact on Electoral College allocation (proportional vice winner take all) and on participation in the rigged two-party presidential debates that are an outrage and offensive to all thinking citizens who appreciate the divesity that once chacterized the debates as managed by the League of Women Voters.