WASHINGTON (AP) -- The White House is urging dockworkers and shipping companies to reach agreement "as quickly as possible" on a contract extension for East Coast and Gulf Coast dockworkers whose existing pact expires this week.

Obama spokesman Matt Lehrich says the White House is monitoring the situation closely and urges the parties to "continue their work at the negotiating table to get a deal done as quickly as possible."

Talks between the dockworkers and shipping companies broke down Dec. 18 amid unresolved issues such as wages and container royalties -- the payments to union workers based on cargo weight. The International Longshoremen's Association and the U.S. Maritime Alliance are expected to meet this week.

The National Retail Federation has asked the Obama administration to use "all means necessary" to prevent a strike.