KSC spokesman George Diller said that "it is increasingly likely" that NASA would not make a launch attempt Friday. He added that postponement until sometime next week was under consideration.

Endeavour and its U.S.-Russian crew had been scheduled to launch Thursday but those plans were dashed when a Progress cargo carrier failed to firmly dock at the station after it arrived at the complex Wednesday.

Engineers since have determined that a one-foot (30-centimeter) piece of cable 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.

Consequently, the cargo carrier cannot be opened until the errant cable is removed so that the Progress can be firmly docked to the outpost.

The problem prompted NASA managers to tentatively reschedule the Endeavour flight for Friday. The KSC launch team now is readying the shuttle for an attempt that would come at about 6:50 p.m. EST (2350 GMT) Saturday.

A spacewalk aimed at fixing the Progress problem, meanwhile, is tentatively scheduled for Monday. The 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.

Russian cosmonauts Vladimir Dezhurov and Mikhail Turin then would venture outside the station, using some type of tool to dislodge the cable so that the Progress could be securely docked to the outpost.

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 -- Dezhurov and Turin -- are scheduled to return to Earth aboard Endeavour. That trio has been onboard the station since August.

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, 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.

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.

NASA officials said earlier this week that a delay beyond Dec. 6 could force NASA to postpone the mission until early next year. Air Force officials, however, now indicate that some of the previously scheduled operations might be rescheduled.

In that case, it appears that launch opportunities, if necessary, could open up for Endeavour between Dec. 10 and Dec. 14.