The plot thickens in the controversy over the federal government’s decision to ship weapons-grade plutonium from Colorado to South Carolina for temporary storage. Arms-control advocates and Democratic politicians in South Carolina allege that the Bush administration is backing a shipment plan in order to improve the re-election prospects of Sen. Wayne Allard (R-Colo.). Allard, who is in a close race against Democrat Tom Strickland, has made getting rid of the plutonium central to his campaign. Jim Hodges, the Democratic governor of South Carolina, opposes the shipment plan and yesterday accused the White House of blatant politicking: “It seems like the concerns of South Carolina voters are somehow secondary to the concerns of Colorado voters. I’ll leave it to your imagination as to why that is.” We’ll spell it out: The administration doesn’t want to lose a Republican seat in the Senate.