Obama builds Iran nuclear deal support one vote at a time

By Richard Cowan WASHINGTON (Reuters) - President Barack Obama is gradually building support in the U.S. Congress for an international nuclear deal with Iran, working the phones to counter lobbying against the pact and sending a letter to lawmakers urging them to support it. Obama needs to win the backing of one-third of either the House of Representatives or the Senate to prevent Republicans from killing the nuclear deal announced in July. Signed by world powers and Iran, the agreement would re