(Reuters) - The Pentagon on Wednesday rejected for now a Navy plan under which Northrop Grumman Corp. and General Dynamics Corp. would compete for, rather than split, a potential $20 billion contract to build a new class of guided missile destroyer. The action dovetails with moves in Congress aimed at blocking a winner-take-all approach, which the Navy has said could trim $300 million from the cost of each DD(X) destroyer. Any change to the existing production-sharing strategy "is premature at this time," Michael Wynne, the Pentagon's chief weapons buyer, said in a Defense Department statement. Wynne authorized the Navy to seek additional input from Los Angeles-based Northrop and Falls Church, Virginia-based General Dynamics on any future change in acquisition strategy.