YAKIMA — U.S. representatives from Washington and Oregon yesterday urged Congress to restore full funding for cleanup of the highly contaminated Hanford nuclear reservation.

For 40 years, Hanford made plutonium for the nation's nuclear-weapons arsenal, beginning with the top-secret Manhattan Project to build an atomic bomb during World War II. Cleanup costs at the nation's most contaminated nuclear site are expected to total $50 billion to $60 billion by the time the work is completed in 2035.

The fiscal 2005 budget marked the peak year for cleanup funding at about $2.1 billion. Under the 2006 budget proposed by President Bush, the allocation would fall more than $260 million to about $1.8 billion.

The cuts go too far, said a letter to House budget writers signed by all 14 representatives from Washington and Oregon. Full funding is critical to sustain the cleanup momentum and keep a skilled work force on the job, they wrote.

"Today's action is a testament to our region's bipartisan commitment to cleaning up Hanford," Rep. Doc Hastings, R-Wash., said in a news release.

Energy Secretary Samuel Bodman cited his agency's successful completion of a number of cleanup projects at Hanford as one reason for funding decline. The Energy Department faces "legal difficulties" related to Hanford, he added, and for that reason, agency officials don't think they can justify spending more there.