A bill to slap new sanctions on Iran if it goes back on an interim deal under which it agreed to limit its nuclear program has gained support since it was introduced in December, aides to U.S. senators have told Reuters.
The bill requires further reductions in Iran's oil exports and would apply new penalties on other industries if Iran either violates the interim agreement or fails to reach a final comprehensive deal.
President Barack Obama is opposed to the bill and has threatened to veto it even if lawmakers pass it.
The "Nuclear Weapon Free Iran Act" had about 48 co-sponsors in the 100-member Senate on Monday, up from 26 when the bill was introduced on December 19, an Senate aide said.
"Expect that number to keep growing over next couple of days as folks who were out of town and staff get back in," the aide told Reuters.
The bill was introduced by Robert Menendez, the chairman of the Senate Foreign Relations Committee, and Mark Kirk, a Republican from Illinois.
"We expect several Democrats to kind of cross the picket line and come on board this week," the aide said.
While the bill has gained support, it remains uncertain if backers can put together the two-thirds majority in the Senate needed to override a veto by Obama.
The Obama administration has insisted the bill would damage delicate talks being held between Iran and world powers over the nuclear program, which Tehran says is for peaceful purposes. Iranian Foreign Minister Mohammad Javad Zarif has threatened that a new sanctions law would kill the interim agreement.
The Obama administration has waged an aggressive campaign to convince lawmakers to postpone passing new sanctions on Iran.
Obama recently told lawmakers that Iran would make progress in its ability to build a nuclear weapon if there is no diplomatic deal to halt or roll back its nuclear program.
While senior Democrats in the Senate like Menendez, from New Jersey, and Charles Schumer, from New York, support the new sanctions, there is a strong bloc of opposition in the party, reported Reuters.
According to the report, ten Democratic senators, all leaders of committees, sent a letter to Senate Majority Leader Harry Reid last month expressing their opposition to the bill.
A bipartisan group of nine senior foreign policy experts have urged Menendez and Kirk not to pass the new sanctions, saying the penalties could potentially move the United States closer to war.
Ryan Crocker, a former ambassador to Iraq and Afghanistan, and Thomas Pickering, former Ambassador to Israel, India and the United Nations, were among signers of a letter to the senators that said a sanctions bill, even if it took effect in six months, would call into question Washington's good faith and possibly isolate the United States among the countries negotiating with Iran.
Lawmakers in Iran have responded to the American measure by drafting a bill of their own to increase the country’s level of uranium enrichment.
The bill, if passed, would oblige the government in Tehran to produce 60-percent enriched uranium.