But a spacewalk almost certainly will be required to secure the supply ship to the station. Consequently, project officials are trying to decide whether that work should be done before, during or after Endeavour's planned weeklong stay at the outpost.

Mission managers, meanwhile, are expected to decide early Friday whether to press ahead with plans to launch Endeavour.

"There's a very good possibility that we'll be ready (Friday) morning with a decision to proceed with the launch," senior NASA station project manager Jim Van Laak told reporters during a news briefing Thursday afternoon.

If that's not the case, Van Laak said NASA and the Russian Aviation and Space Agency likely would opt to delay the launch until Saturday or Sunday.

Endeavour and its U.S.-Russian crew had been scheduled to launch Thursday but those plans were dashed when the Progress cargo carrier failed to firmly dock at the station the day before.

Engineers since have determined that what appears on videotape to be a one-foot (30-centimeter) piece of cable, cord or wire prevented latches on the Progress and the station's Russian-built crew quarters from snapping shut.

A drogue-and-probe docking mechanism now is holding the cargo carrier to the aft end of the station's so-called Zvezda, or Star, module. But until the 16 latches can be closed, no airtight seal can be formed between the Progress and the station.

Launched Monday from Baikonur Cosmodrome in Kazakhstan, the Progress is filled with 2.5 tons of food, supplies, equipment and fuel for the fourth full-time station crew, a trio to be launched to the outpost aboard Endeavour.

The Expedition Four crew includes Russian cosmonaut Yuri Onufrienko and two American flight engineers -- Daniel Bursch and Carl Walz -- the three of whom plan to live and work aboard the outpost until next May.

Current station skipper Frank Culbertson and his two cosmonaut colleagues -- Vladimir Dezhurov and Mikhail Turin - are scheduled to return to Earth aboard Endeavour. That trio has been onboard the station since August.

During a transoceanic teleconference Thursday, Russian space officials recommended proceeding with the Endeavour launch and then staging a spacewalk to fix the Progress problem next Monday.

Their plan calls for the probe on the cargo carrier's docking mechanism to be extended, creating an eight- to 12-inch (20- to 30-centimeter) gap between the Progress and the Zvezda module.

Dezhurov and Turin then would venture outside the station, using some type of tool to dislodge the errant cable so that the Progress could be firmly docked to the outpost.

Still unclear, however, is whether such an excursion could be added to a packed slate of work already scheduled for Endeavour's stay at the outpost, a visit that cannot be extended due to limited shuttle fuel supplies.

That work includes the transfer of some 6.5 tons of supplies and equipment from a shuttle-borne moving van to the outpost as well as a U.S. spacewalk to repair a balky motor drive on the station's American-made solar arrays.

Van Laak said NASA officials are considering delaying the U.S. spacewalk -- which is to be carried out by Endeavour mission specialists Daniel Tani and Linda Godwin -- until after the shuttle departs the station.

In that case, Expedition 4 flight engineers Bursch and Walz -- who trained earlier this month to do the job -- would be pressed into service to carry out the work.

NASA mission managers, meanwhile, face a deadline of sorts for launching Endeavour. As it stands, NASA only has until Dec. 6 to launch the station crew rotation mission.

After that, the mission might have to be postponed until early January.

The reason: Previously scheduled classified operations effectively would block any shuttle launch attempt prior to Dec. 14 on the Air Force's Eastern Range, which provides tracking and range safety services for all launches from Florida's Space Coast.

The classified operations -- which include mission dress rehearsals for the planned January 15 launch of an Air Force Titan 4 rocket and a military communications satellite -- now are scheduled between Dec. 7 and Dec. 14.

Complicating matters is the fact that from Dec. 15 through Jan. 2, Endeavour cannot be launched because the station will be flying in an orbit that would expose a docked shuttle to high temperatures that could foul spaceship systems.

Consequently, any delay beyond Dec. 6 could force NASA to postpone the mission until next year unless the Air Force agrees to reschedule its classified operations. And with the Christmas and New Year's holidays at hand, NASA officials have said Jan. 6 likely would be the earliest date for any launch attempt next year.

A launch on Friday, meanwhile, would lead to a Dec. 11 landing here at NASA's coastal Florida spaceport. For Culbertson and his colleagues, a touchdown that day would cap a 121-day stay in space.