The chances of NASA launching the space shuttle Atlantis this week diminished by the hour Sunday as the space agency worried about the effect of a lightning strike at the launch pad and the threat of Hurricane Ernesto.

NASA leaned toward delaying the launch until Tuesday to give engineers more time to figure out if the lightning strike Friday damaged the spacecraft's solid fuel rocket boosters.

However, the threat of Hurricane Ernesto was diminishing the chances of a shuttle launch for later in the week.

• Click here to visit FOXNews.com's Space Center.

A new National Hurricane Center forecast at 11 a.m. put the eye of Ernesto on Florida's west coast, due west of the Kennedy Space Center, on Thursday morning. NASA hurricane policy is to move shuttles back to the protection of the massive Vehicle Assembly Building before a storm hits with wind greater than 45 mph, but it takes nearly two days to roll a shuttle off the launch pad safely.

That lessens the possibility of a Tuesday launch, NASA spokesman Bruce Buckingham said.

No decision was to be made until after a 5 p.m. hurricane center updated forecast, NASA spokesman George Diller said.

The launch was originally scheduled for Sunday afternoon, but NASA pushed it back to Monday so engineers and technicians could have more time to determine if ground and flight systems were affected by Friday's lightning.

There were no immediate indications that any damage was caused by the lightning bolt, one of the most powerful recorded at a Kennedy Space Center launch pad. Rather than hitting the shuttle directly it struck a wire attached to a tower used to protect the spacecraft from such strikes -- but it created an electrical field around the vehicle.

The solid rocket booster system wasn't powered up at the time so engineers didn't get enough data about its effect on the boosters, which provide the main thrust to lift the shuttle off the launch pad, said NASA spokesman Bruce Buckingham.

Atlantis' planned mission is the first of 15 flights scheduled to finish constructing the half-built space station before the cargo-carrying shuttles are retired in 2010. Construction has been on hiatus since the 2003 Columbia disaster, which killed seven astronauts.

• Click here to visit FOXNews.com's Space Center.