All presidential candidates who have qualified for placement on enough state ballots to win the Electoral College and the Presidency of the U.S. must be included in the presidential debates.
Why should people sign?
Libertarian Party candidates Gary Johnson and Jim Gray, along with Green Party candidates Jill Stein and Cheri Honkala, have qualified for enough state ballots and are receiving taxpayer dollars in the form of FEC matching funds. American taxpayers and voters have a clear interest in having their ideas, positions, and voices included in the major presidential and vice presidential debates.
Currently, the Commission on Presidential Debates excludes all candidates who do not poll at 15% or higher in at least 5 national polls (raised from 5% after that threshold secured Ross Perot a spot in the 1992 debates). However, most national polls exclude third party candidates, making it nearly impossible to achieve the required percentage of support.
The Commission on Presidential Debates is a private "nonprofit corporation controlled by the Democratic and Republican parties and has run each of the presidential debates held since 1988... Prior to this, the League of Women Voters moderated the 1976, 1980, 1984 debates before it withdrew from the position as debate moderator with this statement after the 1988 Presidential debates: 'the demands of the two campaign organizations would perpetrate a fraud on the American voter.' [source: Wikipedia]