Fed up with gridlock on Capitol Hill, an unlikely coalition of leading environmental, labor and civil rights groups is mobilizing to push for an overhaul of Senate filibuster, campaign finance and voting rules.

Organizers say this emerging “democracy” movement is prompting mainstream progressive groups to branch beyond their core issues to take on procedural and institutional battles typically left to government watchdogs. The Senate filibuster, unrestricted political money and curbs on ballot access are all blocking action on broader policy issues, from clean energy to jobs, they argue.

Key organizers include the Sierra Club, Greenpeace, the Communications Workers of America and the NAACP, whose leaders are convening a Dec. 10 meeting in Washington of some 75 progressive organizations.

“Lots of people have had lots of different agendas, and it’s time to unite and bring together organizations that haven’t been good government groups, and start to engage in these process issues,” said George Kohl, a senior director at the CWA.

The coalition has no formal name or policy agenda yet, but it has rallied behind certain basic goals. The leaders are part of a broader effort dubbed Fix the Senate Now that this week relaunched a 2010 lobbying campaign to push for curbs on the Senate filibuster. That coalition also includes the Alliance for Justice, Common Cause and the United Auto Workers.