WASHINGTON (Reuters) - Two leading Senate Democrats said on Tuesday they had decided to support Chuck Hagel's nomination as U.S. defense secretary, providing a critical boost to the former Republican senator's chances of getting the job. U.S. Senator Chuck Schumer of New York, the No. 3 Democrat in the Senate, said his concerns over Hagel's positions on Israel, Iran and other issues were addressed after they met for about 90 minutes on Monday. He described Hagel as "forthcoming and sincere. ...