LOS ANGELES – There is finally a break in the clerical workers strike crippling the twin ports of Los Angeles and Long Beach with both sides agreeing this afternoon to federal mediation.

At a press conference today L.A. Mayor Antonio Villaraigosa labeled the agreement to head to mediation – a move the striking workers had resisted till now –an encouraging sign that could end the strike. He said the parties kept at negotiations throughout the night.

CNN reported the mediator will start working on the dispute tomorrow.

The striking clerical workers are part of the 800-member International Longshore and Warehouse Union Local 63 Office Clerical Unit and have been on strike since Nov. 27 against a 14-employer group of shipping lines and terminal owners. What intensified the strike is that the picket lines were honored by the 10,000 regional members of the ILWU.

The clerical workers have been picketing seven of eight Los Angeles terminals and three of six Long Beach terminals even though an arbitrator ruled their walkout last Tuesday as invalid. Their strike and the support it has received from other ILWU members not crossing the picket lines have essentially shut down the affected terminals. The resulting slowdown has cost the busy complex about a billion dollars a day, port officials say.

A union spokesman told the Wall Street Journal the clerical workers fear their jobs are being outsourced to low cost countries in Central America and Asia. But the port employers association told the Wall Street Journal that was a “myth” and claimed it has “offered to guarantee no workers will be laid off, among other outsourcing protections.”

ILWU leaders want jobs traditionally performed by their members to remain as union work and subject to the union’s contract terms, even after individuals holding those positions retire. The employers, on the other hand, want the freedom to fill jobs that need to be filled, and accuse the union of trying to featherbed work that is unnecessary, even after jobs are lost through retirement.

Combined, the Port of Long Beach and the Port of Los Angeles move 40 percent of all containerized trade in the US. More than $300 billion worth of goods flow through the two ports annually.