The Libertarian Party and Green Party and their 2012 candidates for president are readying a legal complaint against the Commission on Presidential Debates...[it] argues that a "cognizable political campaign market" is being corrupted by the commission's rules. The commission, a private entity set up after the League of Women Voters' 1992 debates allowed third party candidate Ross Perot to participate, has withstood yearly assaults from the likes of Ralph Nader, Pat Buchanan, and former Congressman Bob Barr.