With the Senate poised to vote as early as today on a proposed nuclear waste disposal site at Nevada’s Yucca Mountain, two wavering lawmakers have agreed to support the site in exchange for a favor in their own state. Republican Sens. Robert Bennett and Orrin Hatch, both of Utah, met yesterday with Energy Secretary Spencer Abraham, who promised to oppose a private nuclear dump on a Native American reservation in Utah in exchange for the senators’ support of the Yucca Mountain repository. “Faced with the choice of having [the waste] come through Utah or to Utah — and in much greater quantities — I decided I would rather have it come through,” Bennett said. Critics of the Yucca Mountain plan say nuclear waste will be shipped through thousands of communities en route to Nevada, making them vulnerable to accident or attack. Proponents of Yucca Mountain say they now have a majority, which might spell the end of two decades of struggle to find a storage space for thousands of tons of high-level radioactive waste from the nation’s commercial reactors and nuclear weapons plants.