Kennedy Space Center, Florida (CNN) -- NASA may decide Sunday morning whether the delayed final launch of the space shuttle Endeavour will occur Monday afternoon, the space agency said.
Friday's launch was scrubbed due to concerns with the shuttle's heating system. The target time is now 2:44 p.m. Monday.
According to a Saturday statement, NASA technicians confirmed the cockpit control fuse panel is working.
"Teams began testing thermostats associated with the heater connected to the fuel line for the (auxiliary power unit)," NASA said. "Initial reports indicate the thermostat side that failed during Friday's launch countdown still is not working, as expected.
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"Teams will continue additional testing to help determine whether the thermostat is receiving a current or whether the issue is being caused by another part of the system."
Cmdr. Mark Kelly's wife, injured U.S. Rep. Gabrielle Giffords, traveled to Florida to watch the shuttle's ascent.
President Barack Obama and the first lady also went to the launch site, and Obama personally visited with Giffords Friday for about 10 minutes, a White House official said.
Three months ago, Giffords was nearly killed when a would-be assassin shot her in the head during a meeting with constituents in Tucson, Arizona. It was not immediately clear if Giffords' doctors -- who are overseeing her lengthy rehabilitation -- will allow her to remain in Florida for the duration of the delay.
Giffords' office said Friday that her travel plans are "undetermined," according to a statement.
Kelly leads a crew that includes pilot Gregory Johnson; mission specialists Michael Fincke, Greg Chamitoff and Andrew Feustel; and European Space Agency astronaut Roberto Vittori.
Four spacewalks are planned for the mission. The space walkers will retrieve experiments, install new ones, refill tanks and lubricate parts at the International Space Station.
