As presidential election season nears, the Commission on Presidential Debates (CPD) is once again being encouraged to include a third-party or independent candidate in next year's debates. A new group of more than 40 current and former elected officials is now lobbying the CPD to open its doors.

The bipartisan group Change the Rule - whose signatories include Sen. Angus King, former FBI director Michael Hayden, retired Gen. Stanley McChrystal and former senators Bob Kerrey and Joe Lieberman - has launched a national campaign taking on the CPD's controversial and exclusionary rules that they claim essentially prevent any candidate outside of the two-party system from participating in the presidential debates, reports The Hill. The group contends that the absence of third-party candidates ultimately harms democracy and serves the two major parties' interests.

The CPD was founded in 1988 by the Republican and Democratic parties, and its unelected members have since organized presidential and vice-presidential debates. The commission has unilaterally decided that in order to participate in the debates, a candidate must poll higher than 15 percent in at least five polls prior to the debates.

Change The Rule argues that any candidate not backed by a major party has little chance of getting into the debates. Since the CPD rules create unreasonable fundraising requirements, only candidates backed by millions of dollars have a shot at participating. The group estimated that to reach the 15 percent poll requirement, a non-major party candidate would have to spend some $300 million to align himself or herself with the major party candidates, according to The Hill.

The group sent private letters to CPD board members in January requesting that the commission remove some of its qualifications for nonmajor party candidates.

"Because the current rule affords independent candidates no chance to get into the debates, it dissuades men and women with extraordinary records of service to this country from running for President," the letter provided to The Hill says. "As a director of the CPD, you could ignore this complaint and wait for the ensuing legal process to play out. We think that would be a missed opportunity and an unfortunate mistake."

Change the Rule said that upon receiving the CPD's two-sentence response expressing gratitude for the input, it decided to take the fight public.

"A separate legal entity has filed a complaint with the Federal Election Commission and Change the Rule says legal challenges could follow over a rule the group says is in violation of federal law," reported The Hill.

Five-time candidate for president Ralph Nader previously sued the CPD over its allegedly unfair rules, as did former New Mexico Governor and Libertarian Party presidential candidate Gary Johnson, as well as ormer Green Party presidential candidate Jill Stein.

Change the Rule instead proposes that the commission determines who can participate in the debates based on ballot access. If a third-party candidate can prove that he or she has access to ballots in enough states to theoretically get the 270 electoral votes needed to win the presidency, that candidate should be allowed to participate in the debates, CTR says, reported ABC News.

Presidential debates play a crucial role in informing the public about candidates they might otherwise not hear from or even know existed, but since the CPD's founding, only one third-party candidate - Ross Perot in 1992 - has been allowed to participate in the debates.

Since then, the American political landscape has shifted dramatically away from both major parties. According to a 2014 Gallup survey, 42 percent of Americans say they are political independents belonging to neither party.

"[The two-party system] is not working in the best interests of our country and it needs to be challenged and, in some sense, assaulted," said Lieberman, calling the 15 percent barrier an "unfair obstacle," reported Politico.

While Lieberman said he believes the CPD has good people on its board, he said it was "dominated by the two parties" who have a strong interest in making it difficult for third parties to compete in debates.

"It's not my line, but the fastest-growing party in America is no party," he said. "I grew up in the two- party system and believe it did a good job of coalescing minority groups of opinion. But it's ceased to do that. The parties have become increasingly homogeneous."

In 1998, the CPD's rules prompted renowned journalist Walker Cronkite to speak about the farce that the debates have become. "The debates are part of the unconscionable fraud that our political campaigns have become," Cronkite said. "Here is a means to present to the American people a rational exposition of the major issues that face the nation, and the alternate approaches to their solution. Yet the candidates participate only with the guarantee of a format that defies meaningful discourse. They should be charged with sabotaging the electoral process."