New Mexico Gov. Bill Richardson yesterday suggested when endorsing Sen. Barack Obama in the Democratic presidential race that Sen. Hillary Rodham Clinton should drop out, while a primary-election lawsuit had made it tougher for the former first lady to secure the party's nomination. The one-time candidate's endorsement helped Mr. Obama at the end of a difficult week, giving him the support of another former Clinton administration official who also is a superdelegate and a high-profile Hispanic. "You will be an outstanding commander in chief," Mr. Richardson told the Illinois senator at a rally in Portland, Ore., yesterday. "Above all, you...