Republicans and Democrats are pressuring congressional negotiators to produce legislation imposing the severest penalties on Iran, targeting its energy sector and financial institutions as the United States seeks to weaken Tehran economically and derail its pursuit of nuclear weapons.

"Now is the time to ratchet up the pressure," Rep. Ted Deutch, D-Fla., said in an interview this week.

Rep. Ileana Ros-Lehtinen, R-Fla., chairwoman of the House Foreign Affairs Committee, and Sen. Tim Johnson, D-S.D., chairman of the Senate Banking Committee, have been negotiating behind closed doors for several weeks to reach consensus on sanctions legislation that the House passed in December and the Senate approved in May.

"We owe it to the American people to exhaust every possible non-military option to prevent Iran from acquiring a nuclear weapons capability," Sen. Mark Kirk, R-Ill., said in a statement.