When a Democratic president nominates a federal judge from a state with two Democratic senators — and the Senate itself is controlled by Democrats — a speedy confirmation hearing typically follows. But in an unusual case of intraparty defiance, Senator Robert Menendez of New Jersey is holding up President Obama’s nomination of a judge to the United States Court of Appeals for the Third Circuit, the only time a Democrat has tried to block one of Mr. Obama’s judicial nominees. Mr. Menendez would not comment. But the nominee, Patty Shwartz, has been in a relationship for more than two decades...