President Obama is facing pressure to block a strike that would gridlock U.S. ports from Maine to Texas and risk damaging industries from retail to manufacturing.

Federal mediators have been pushing for a deal between dockworkers and their employers before a Saturday deadline. Talks between the International Longshoremen's Association and the U.S. Maritime Alliance broke down last week amid a dispute over container royalty fees, which are levies that supplement wages.

A walkout would be the first at East Coast and Gulf Coast ports since 1977, and would halt shipments of containerized cargo including clothing, frozen foods, and car parts. Obama would be left to choose between forsaking a pro-labor stance by invoking the 1947 Taft-Hartley Act and allowing a union action that could compound the effects of the fiscal cliff.

The union represents 14,500 dockworkers in East and Gulf Coasts ports, including Philadelphia.

Ports on the Delaware would not be as severely disrupted as some ports, such as New York, because more cargoes arrive here in bulk or smaller crates and on pallets, including plywood, steel, paper, cocoa beans, and fruit.

Longshoremen who handle cargoes not shipped in containers would stay on the job in the event of a strike.

"To throw that kind of a strike on top of the economy right away in January, I'm sure, is something the administration would rather not see," said Mike Asensio, a labor lawyer at Baker Hostetler L.L.P. in Columbus, Ohio.

The Federal Mediation and Conciliation Service, which has guided talks since September, organized a meeting between the two sides this week in an eleventh-hour effort to salvage negotiations. All three parties declined to provide further details on the new talks.

If federal mediation fails, the only remaining tool in the government's arsenal is Taft-Hartley, which empowers the president to intervene in strikes that are deemed national emergencies, said Phillip Wilson, president and general counsel at the Labor Relations Institute in Broken Arrow, Okla.

The act was last invoked by President George W. Bush in 2002 after a lockout closed West Coast ports for 10 days.

The Port Authority of New York and New Jersey said a strike would cost the region an estimated $136 million a week in personal income and $110 million in economic output.

With the fiscal cliff of more than $600 billion in spending cuts and tax increases looming at the end of the year, the president won't be able to linger on the sidelines, said Jock O'Connell, international trade adviser at Los Angeles-based consultant Beacon Economics L.L.C.