The White House on Wednesday hailed the beginning of the end of efforts to plug and contain the BP oil spill in the Gulf of Mexico but said there was still a lot of cleanup work to be done.

White House spokesman Robert Gibbs spoke after BP claimed a significant milestone in sealing its ruptured well for good and as U.S. government scientists reported that nearly three-fourths of the spilled crude had been dispersed or captured or had evaporated.

President Barack Obama's approval ratings have been hurt by public discontent over the government's response to the worst oil spill in U.S. history, and he and his top aides have scrambled to recover lost ground.

It is sort of the beginning of the end of the sealing and containment phase of this operation, Gibbs told reporters.

But he said, Our commitment to those families, to those communities in and along the Gulf Coast, remains the same.

There is still lots of work to do, and this government will be there every step of the way, he said.

Thad Allen, the top government official overseeing the oil spill response, said the job would not be complete until a relief well is finished later this month, but he called the static kill operation a significant step.

(Writing by Matt Spetalnick, Editing by Sandra Maler)