WASHINGTON  President Obama’s proposed budget cuts off most money for the Yucca Mountain nuclear waste project, a decision that fulfills a campaign promise and wins the president political points in Nevada  but raises new questions about what to do with radioactive waste from the nation’s nuclear power plants.

The decision could cost the federal government additional billions in payments to the utility industry, and if it holds up, it would mean that most of the $10.4 billion spent since 1983 to find a place to put nuclear waste was wasted.

A final decision to abandon the repository would leave the nation with no solution to a problem it has struggled with for half a century.

Lawyers are predicting tens of billions of dollars in damage suits from utilities that must pay to store their wastes instead of having the government bury them, with the figure rising by about a half-billion dollars for each year of additional delay.