A lesser-known U.S. Senate candidate has filed suit in federal court seeking inclusion in a debate scheduled for next month between former governors Timothy M. Kaine (D) and George Allen (R).

Kaine and Allen, the prohibitive frontrunners for their parties’ nominations in the race to succeed retiring Sen. James Webb (D), are slated to face off Dec. 7 in Richmond as part of the annual AP Day at the Capitol. Several other hopefuls are running for the seat, but the debate rules say a candidate needs to average 15 percent or better in published, non-candidate primary polls, and raise at least 20 percent as much money as his or her party’s frontrunner by the end of October in order to participate.

Republican candidates Jamie Radtke and Timothy Donner complained at the time that the rules were unfair, and now Democratic candidate Julien Modica has gone a step further, filing suit in the U.S. District Court in Alexandria against the Virginia Capitol Correspondents Association and the Associated Press.

(Disclosure: Washington Post staff writer Anita Kumar is a member of the VCCA and serves on a committee that helped organize the debate.)

Modica’s lawsuit argues that excluding him from the December debate ”based on standards, defined and created behind closed doors, that, theoretically and practically, only two former Virginia Governors can meet is like excluding your youngest son from Christmas celebrations just because he lives in Northern Virginia.”

The suit alleges that the debate rules deprive him of his civil rights, and of access to his fair share of television time.

Candidates in other races excluded from debates have sought remedy from the courts before, usually without success. Past complainants include independent candidate Ross Perot, who failed in a legal effort to be included in the 1996 presidential debates.

“It’s a very tough road to successfully litigate one’s way into a political debate,” said Elliot Berke, co-chair of the Political Law Group at McGuireWoods. “The courts have historically been pretty deferential to debate sponsors, providing they stick to pre-established objective criteria to determine which candidates may participate.”

Allen agreed this week to participate in three GOP primary debates being staged next year by the Republican Party of Virginia. Currently, there are no Democratic primary debates planned. Businesswoman Courtney Lynch is running for the Democratic nod, in addition to Kaine and Modica.

Modica, who runs a veterans health care organization, ran losing campaigns for Senate in 2008 and the 10th Congressional District seat in 2010. Modica was convicted of bank fraud in 1994 under another name, Julien K. Dilks.

Representatives of the AP and VCCA had not responded to a request for comment as of this posting.