WASHINGTON  The Bush administration will recommend that Congress give up the idea of a second nuclear waste dump, dropping a grand bargain struck in the 1980s, and instead vote to enlarge the repository now proposed in Nevada, the director of the Energy Department’s civilian radioactive waste management program said on Thursday.

The director, Edward F. Sproat III, who is in charge of work on the proposed repository at Yucca Mountain, 100 miles northwest of Las Vegas, said that the process of trying to open one repository had been so slow and expensive that this was not a good time to start looking for another.

The future of the entire repository program may be in flux anyway because President-elect Barack Obama has called for finding another solution. But Mr. Sproat noted that the law called for his department to pursue the opening of the Yucca site.

Originally, the government promised utility companies that it would begin accepting nuclear waste in 1998 and began accepting payments from them of one-tenth of a cent per kilowatt-hour generated at their reactors. The government now predicts that a waste repository will open by 2020 at the earliest, and clearing the backlog could take many decades. Because of the delay, the government will owe commercial damages to the utilities of $11 billion or more.