The setback, yet another in the nine-week effort to stop the gusher, came as thick pools of oil washed up on Pensacola Beach in Florida and the Obama administration tried to figure out how to resurrect a six-month moratorium on deepwater drilling.
When the robot bumped the system just before 10 a.m. Wednesday, gas rose through the vent that carries warm water down to prevent ice-like crystals from forming, Coast Guard Adm. Thad Allen said.
Crews were checking to see if crystals had formed before putting it back on. BP spokesman Bill Salvin could not say how long that might take.
"We're doing it as quickly as possible," he said.
Before the problem with the containment cap, it had collected about 700,000 gallons of oil in 24 hours and sucked it up to a ship on the surface. That's oil that's now pouring into the Gulf. Another 438,000 gallons was burned on the surface by a different system that was not affected by the issue with the cap.
A similar problem doomed the effort to put a bigger containment device over the blown-out well in May. BP had to abandon the four-story box after the crystals called hydrates clogged it, threatening to make it float away.
The smaller cap, which had worked fine until now, had been in place since early June. To get it there, though, crews had to slice away a section of the leaking pipe, meaning the flow of oil could be stronger now than before.
The current worst-case estimate of what's spewing into the Gulf is about 2.5 million gallons a day. Anywhere from 67 million to 127 million gallons have spilled since the April 20 explosion on the Deepwater Horizon rig that killed 11 workers and blew out the well 5,000 feet underwater. BP PLC was leasing the rig from owner Transocean Ltd.
The Obama administration was plotting its next steps Wednesday after U.S. District Judge Martin Feldman in New Orleans overturned a moratorium on new drilling, saying the government simply assumed that because one rig exploded, the others pose an imminent danger, too.
Feldman, appointed by President Ronald Reagan in 1983, has reported extensive investments in the oil and gas industry, including owning less than $15,000 of Transocean stock, according to financial disclosure reports for 2008, the most recent available. He did not return calls for comment on his investments.
The White House promised an immediate appeal of his ruling. The Interior Department imposed the moratorium last month in the wake of the BP disaster, halting approval of any new permits for deepwater projects and suspending drilling on 33 exploratory wells.
Interior Secretary Ken Salazar said in a statement that within the next few days he would issue a new order imposing a moratorium that eliminates any doubt it is needed and appropriate.
"It's important that we don't move forward with new drilling until we know it can be done in a safe way," he told a Senate subcommittee Wednesday.
Several companies, including Shell and Marathon Oil, said they would await the outcome of any appeals before they start drilling again.
Asked about it Wednesday on NBC's "Today" show, BP managing director Bob Dudley said his company will "step back" from the issue while it investigates the rig explosion.
BP said Wednesday that Dudley has been appointed to head the new Gulf Coast Restoration Organization, which is in charge of cleaning up the spill. He takes over from BP CEO Tony Hayward, who has been widely criticized for his handling of the crisis.
In Florida, dozens of workers used shovels to scoop up pools of oil that washed up overnight, turning the sand orange.
Tar balls have been reported as far east as Panama City, Fla., and heavier oil is predicted to wash ashore further east along the coast line in the coming days. Oil has also washed up on beaches in Alabama and coated wetlands in Louisiana.
Associated Press Writer Curt Anderson in Miami and Melissa R. Nelson contributed to this report.