WASHINGTON, March 4 (Reuters) - A majority of the U.S. Senate on Wednesday backed President Donald Trump's military campaign against Iran, voting to block a bipartisan resolution aiming to stop the air war and require that any hostilities against Iran be authorized by Congress.As voting continued, the tally in the 100-member chamber was 52-47 not to advance the war powers resolution. (Reporting by Patricia Zengerle; Additional reporting by Richard Cowan and Noland D. McCaskill; editing by Mark P...