Federal mediators said the International Longshoremen's Association and the U.S. Maritime Alliance appeared to have resolved -- in principle -- the issue of container royalties, fees paid by shipping companies that are used to supplement worker wages and benefits, The Washington Post reported.
The union and the shipping companies will extend the deadline 30 days while they work on remaining issues on a new collective bargaining agreement.
The breakthrough averted the walk-off by 14,500 dock workers from Houston to Boston this weekend, a move that could have been disruptive to the U.S. economy.
The Federal Mediation and Conciliation Service didn't release details of the tentative agreement but described the latest event as a breakthrough.
"What I can report is that the agreement on this important subject represents a major positive step toward achieving an overall collective bargaining agreement," FMCS Director George Cohen told the Post. "While some significant issues remain in contention, I am cautiously optimistic that they can be resolved in the upcoming 30-day extension period."
Businesses urged President Barack Obama just before Christmas to ensure the affected ports would remain open by invoking the Taft-Hartley Act, which restricts activities and power of labor unions, The Hill reported.
President George W. Bush invoked Taft-Hartley in 2002 to end an 11-day lockout at 29 West Coast ports.