WASHINGTON — The Obama administration’s decision to bypass Nevada’s Yucca Mountain as a nuclear waste repository should give Senate Majority Leader Harry Reid a boost in his bid for a fifth term. The action is not doing another endangered Democrat, Sen. Patty Murray of Washington, any favors. And the same could be said for Democratic lawmakers in South Carolina who have distanced themselves from the administration’s decision. Democratic Reps. John Spratt and Jim Clyburn have been particularly critical of shelving Yucca in recent months. Washington and South Carolina are plaintiffs in a lawsuit designed to keep Yucca Mountain as an...