CAPE CANAVERAL (AP) – Thunderstorms forced NASA to delay the fueling of space shuttle Endeavour, but launch managers held out hope that the bad weather would ease and let them take a shot at an early Wednesday liftoff.

Right at the time fueling should have begun Tuesday night, thunder rumbled across the launch site and it was drizzling.

This is NASA’s second attempt to launch Endeavour and seven astronauts on the space station construction mission and the last one this month. If Endeavour isn’t flying by Wednesday, it will have to make way for an unmanned moon shot and wait until July.

A leak in a hydrogen gas vent line thwarted Saturday’s attempt, the same kind of problem that stalled a shuttle flight in March. The same sort of repairs were done.

The severe thunderstorms were actually to the north and west of Kennedy Space Center, but they posed a threat of lightning at the launch pad, a fueling violation.

NASA’s launch team could wait as long as 1 1/2 hours or more to start pumping more than 500,000 gallons of liquid hydrogen and oxygen into Endeavour’s external fuel tank. The storms were not dissipating as quickly as expected, however, and more were popping up elsewhere.