NEW ORLEANS, LA --A storm brewing in the Caribbean brought the deep-sea effort to plug the ruptured oil well to a near standstill Wednesday just as BP was getting tantalizingly close to going in for the kill. Work on the relief well -- now just days from completion -- was suspended, and the cap that has been keeping the oil bottled up since last week may have to be reopened, allowing crude to gush into the sea again for days, said retired Coast Guard Adm. Thad Allen, the government's point man on the crisis. "This is necessarily going to be a judgment call," said Allen, who was waiting to see how the storm developed before deciding whether to order any of the ships and crews stationed some 50 miles out in the Gulf of Mexico to head for safety. The cluster of thunderstorms passed over Haiti and the Dominican Republic on Wednesday, and forecasters said the system would probably move into the Gulf over the weekend. They gave it a 50 percent chance of becoming a tropical depression or a tropical storm by Friday. Crews had planned to spend Wednesday and Thursday reinforcing with cement the last few feet of the relief tunnel that will be used to pump mud into the gusher and kill it once and for all. But BP put the task on hold and instead placed a temporary plug called a storm packer deep inside the tunnel, in case it has to be abandoned until the storm passes. "What we didn't want to do is be in the middle of an operation and potentially put the relief well at some risk," BP vice president Kent Wells said. If the work crews are evacuated, it could be two weeks before they can resume the effort to kill the well. That would upset BP's timetable, which called for finishing the relief tunnel by the end of July and plugging the blown-out well by early August. Scientists have been scrutinizing underwater video and pressure data for days, trying to determine if the capped well is holding tight or in danger of rupturing and causing an even bigger disaster. If the storm prevents BP from monitoring the well, the cap may simply be reopened, allowing oil to spill into the water, Allen said. BP and government scientists were meeting to discuss whether the cap could be monitored from shore. As the storm drew closer, boat captains hired by BP for skimming duty were sent home and told they wouldn't be going back out for five or six days, said Tom Ard, president of the Orange Beach Fishing Association in Alabama. In Florida, crews removed booms intended to protect waterways in the Panhandle from oil. High winds and storm surge could carry the booms into sensitive wetlands. Also, Shell Oil began evacuating employees out in the Gulf. Even if the storm does not hit the area directly, it could affect the effort to contain the oil and clean it up. Hurricane Alex stayed 500 miles away last month, yet skimming in Alabama, Mississippi and Florida was curtailed for nearly a week. The relief tunnel extends about two miles under the seabed and is about 50 to 60 feet vertically and four feet horizontally from the ruptured well. BP plans to insert a final string of casing, or drilling pipe, cement it into place, and give it up to a week to set, before attempting to punch through to the blown-out well and kill it. In other spill-related news: -- Four oil giants -- BP was not among them -- agreed to pool $1 billion to form a new company that would respond to offshore oil spills. The company would be able to mobilize within 24 hours to capture and contain spills at depths of up to 10,000 feet, according to the American Petroleum Institute. -- The Times of London quoted unidentified BP sources as saying the company's beleaguered CEO, Tony Hayward, planned to step down by September after a series of PR blunders, including yacht racing during the spill and saying he wanted his life back. But BP said Hayward still had the full support of its board. BP's broken well spewed somewhere between 94 million and 184 million gallons into the Gulf before the cap was attached. The crisis -- the biggest offshore oil spill in U.S. history -- unfolded after the BP-leased Deepwater Horizon rig exploded April 20, killing 11 workers.