A bill to lift the 40-year-old ban on U.S. oil exports passed the Senate Banking Committee on Oct. 1, but the future of the measure is uncertain in the full chamber, after a controversial amendment was added to it.

The bill, sponsored by Senator Heidi Heitkamp a Democrat from oil-producing North Dakota, passed 13 to 9. Heitkamp was the only Democrat to vote for the measure.

Senator Pat Toomey, a Republican of Pennsylvania, added an amendment to the bill that would make Iran compensate U.S. victims of Iranian backed terrorism, language that senators said would doom the bill's future.

"The bill is dead," because of the addition of the Toomey amendment that the White House likely opposes, said Senator Jon Tester, a Democrat of Montana.

The White House has said it does not support the Senate's efforts to lift the ban. In addition, the White House said earlier this week it would veto any bill that would prevent the president from providing sanctions relief to Iran until $40 billion dollars in restitution has been paid to American victims of Iranian-backed terrorism.

Toomey said that relaxing the trade restriction could offer his state, which also produces oil, some benefits, but that it would have to be done in a way that does not put jobs at oil refineries and in shipbuilding in danger.

A similar bill to lift the ban passed earlier in the year in the Senate Energy Committee. This bill too was only supported by one Democrat, Senator Lisa Murkowski of oil-producing Alaska, the head of the panel. Backers of the bill need six Democrats to pass the bill if all 54 Republicans vote for it.