The Post reports today:

The Democratic National Committee announced today it will file a lawsuit in U.S. District Court Monday to force Sen. John McCain to stay in the public financing system until he formally accepts the Republican presidential nomination in September.

The lawsuit asks the Court to compel the FEC to conduct an investigation into McCain’s decision to unilaterally withdraw from the public financing system, and, should the FEC continue to fail to do so, to allow the DNC to sue McCain directly for disobeying campaign finance laws.

. . .

The complaint faces some significant hurdles. For one, the FEC is hamstrung from dealing with the complex legal issues by a shortage of commissioners — four of six seats are vacant pending senate confirmations — and each additional step in the suit would drag out the process. So long as it remains unresolved, McCain will be able to continue to spend above the primary limits.

Then there is the McCain campaign’s argument — crafted by the candidate’s lawyer, a former FEC chairman — that public financing is voluntary, and McCain had every right to withdraw from the system when it became clear the campaign wouldn’t need federal matching money.

. . .

DNC General Counsel Joe Sandler said he believes McCain’s decision to backstop a critical bank loan with the promise to use public funds as collateral, if necessary, was the decision that locked McCain into the public system.

Assuming the FEC remains unable to resolve that question, Sandler said, the court will have to step in and resolve it. The soonest that could happen, Sandler said, would be sometime in June.

Republican National Committee spokesman Alex Conant called the pending suit “total nonsense.”

“It is now clear that the trial-lawyer Democrats’ idea of campaigning for President is to hire lawyers and file frivolous lawsuits. It’s unfortunate the DNC is now trying to drag the federal courts into their circus as well,” he said in a statement. “As for the lawsuit itself, it is clearly without merit and filed only for public relations purposes. The FEC’s own regulations provide that the Commission must be given 120 days to review any complaint before they may be sued in court. It has only been 49 days since the DNC’s initial meritless complaint to the Commission was filed, and thus we expect this lawsuit to be thrown out at the first opportunity.”

. . .