The Libertarian and Green parties joined a nonprofit group in filing a lawsuit against the Federal Election Commission on Monday to try and change the rules for who is allowed to participate in the general election presidential debates.

The lawsuit, led by the nonprofit group Level the Playing Field, argues that through the Commission on Presidential Debates (CPD), the Democratic and Republican parties have hijacked the presidential debate process and created arbitrary and biased rules governing who can participate in the debates, "for the express purpose of keeping third-party and independent candidates out of debates."

The plaintiffs say that such rules violate FEC guidelines mandating that debates must be held in a nonpartisan manner with candidates selected for participation based on objective criteria.  But according to the suit, the FEC "refuses to carry out its statutory mandate to enforce the federal election laws that the CPD is blatantly violating."

The lawsuit seeks to force the FEC to enforce its rules against the CPD.

"The two major parties have created a series of anti-democratic rules that prevent Americans from learning about candidates that they might prefer to the candidates of the two major parties," it says, adding, "It's obvious that no one can be elected president without participating in the general election debates."

The CPD, a private nonprofit 501(c)(3), was created in 1987 by the Democratic and Republican parties, and has since been solely responsible for choosing which candidates can participate in the presidential and vice presidential debates. The commission is headed by Frank Fahrenkopf, a former head of the Republican National Committee, and President Bill Clinton's former White House press secretary Mike McCurry.

Under CPD's 2012 rules, candidates were required to meet a set of criteria to be invited to the national debates by the CPD: be Constitutionally eligible to hold the presidency, have achieved enough ballot access to hypothetically win the needed 270 electoral votes, and the most controversial rule - poll 15 percent in five national surveys, according to Bloomberg.

The plaintiffs take issue with the last rule, arguing that it's nearly impossible for a candidate outside the two party system to meet the 15 percent polling requirement. They cite research by pollster and campaign strategist Doug Schoen that concludes that an independent candidate would need to spend at least $113 million on advertising just to achieve 60 percent name recognition.

"No third-party or independent candidate has ever raised $113 million. Indeed, $113 million is more than what Mitt Romney's campaign spent to win the republican nomination in 2012," the lawsuit says, noting that this amount is only for advertising and not other costs associated with running a campaign. "Adding up these costs for paid media, campaigning generally, and ballot access, a third-party or independent candidate is looking at a budget of more than $253 million to mount a competitive bid and achieve poll results of 15 percent or more in September."

An administrative complaint and petition for rulemaking was filed with the FEC in September 2014, but Level the Playing Field contends it has so far been ignored, reported The Associated Press.

Executive Director of the CPD, Janet Brown, said in a statement that its candidate selection criteria "have always been designed to ensure that the American public has an opportunity to see the leading candidates debate, regardless of those candidates' party affiliation or independent status," according to AP.

Nicholas Sarwark, chair of the Libertarian National Committee, said the CPD "is another example of the two old parties working hand in hand to keep the American people from hearing real, bold ideas for how to fix this country. Nothing scares them more than having a fresh voice on that debate stage."

He continued: "Any candidate eligible for the Presidency and on enough ballots to be elected should be on the debate stage. Anything else is unfair and perpetrates a fraud on the American voter.  This lawsuit is just one way we are calling out this sham and fighting for all Americans to hear from all of the candidates for President."