ABC News:

The Democratic National Committee is set to file a complaint (.pdf) in federal court against the Federal Election Commission, saying the regulatory agency has failed to act on a request to investigate and take action against Sen. John McCain, the Republican presidential-nominee-in-waiting, for reversing his decision to use public money in the general election.

In February, the DNC asked the FEC to look into whether the McCain campaign violated federal election law by using the promise of federal matching funds for loans and by exceeding the $50 million spending limit for the primaries. The FEC has been unable to make a quorum since the initial DNC request.

Even before the Democrats submitted their February complaint, the FEC mailed the McCain campaign a letter asking for an explanation of an agreement it entered into with Fidelity Bank and Trust Bank of Bethesda. Democrats say that agreement is proof the McCain team violated the law.