The SpaceX Crew Dragon spacecraft is due to launch two NASA astronauts to the International Space Station (ISS) on Saturday.
Bad weather conditions stopped the initial attempt to get astronauts Doug Hurley and Bob Behnken into orbit on Wednesday.
Hurley and Behnken, veterans of two space shuttle flights, have both faced launch delays before.
In a tweet Friday, Hurley said his first shuttle flight was scrubbed five times for weather and technical issues.
"We’re ready for the next launch opportunity!" Behnken tweeted.
Forecasters say it will be touch and go as to whether the rocket will be able to launch on Saturday.
If it goes to plan, the mission will launch at 20:22 BST (15:22 EDT, 19:22 GMT).
The team are expected to try again on Sunday if weather conditions do not permit on Saturday.
If successful, the launch will be the first time American astronauts since July 2011 that a US rocket has made it into space. It will also be the first time a US space agency has used a private company to take its crews to orbit.
The prospective take-off comes after a rocket prototype for SpaceX exploded at their facility in Texas on Friday - an unrelated event to the SpaceX launch.
The firm has been trialling a new design for a future vehicle called Starship and its latest model was destroyed in the blast.
SpaceX was founded by billionaire entrepreneur Elon Musk with the goal of reducing space transportation costs and one day being able to colonise Mars.