Exclusive: U.S. lawmakers push ahead on Iran sanctions - senior senator

By Patricia Zengerle WASHINGTON (Reuters) - Republican and Democratic U.S. lawmakers will press ahead with a plan for more sanctions on Iran, the chairman of the Senate Foreign Relations Committee said on Wednesday, despite White House warnings that they risked derailing nuclear talks. Lawmakers, who say they fear Obama administration negotiators may not take a hard enough line with Tehran, are also at work on a separate bill to have Congress approve any final agreement on Iran's nuclear pr