In what looks to be a clear victory – at least for now – for President Barack Obama, a major effort by the Israel lobby and its most powerful constituent, the American Israel Public Affairs Committee(AIPAC), to pass a new sanctions bill against Iran has stalled in the U. S. Senate. While the legislation, the “Nuclear Weapon Free Iran Act of 2013, ” had gathered 59 co - sponsors in the 100 - member upper chambre by last week, opposition to it among Democrats appears to have mounted in recent days. That opposition apparently prompted Senate Majority Leader Harry Reid, who controls the floor calendar, to back away from a previous commitment to permit a vote on the measure some time over the next few weeks. As a result,AIPACis now reportedly hoping to get the bill through the Republican - dominated House of Representatives. Democratic resistance to the bill, which its critics say is designed to scuttle the Nov. 24 Joint Plan of Action(JPA) between Iran and the so - called P5 + 1(U. S., Britain, France, Russia, China plus Germany) and any chances for a U. S. - Iranian rapprochement, has grown stronger since Sunday’s successful conclusion of an implementation agreement between the two sides and by Obama’s explicit pledge to veto the bill if it comes to his desk. Even one of the bill’s 16 Democratic co - sponsors, Sen. Richard Blumenthal, said this week that he saw no need for a vote “as long as there is progress” in implementing the Nov. 24 accord. The accord, which formally takes effect Jan. 20, will ease some economic sanctions that have been imposed against Iran and ban any new ones in exchange for Tehran’s freezing and, in some cases, a rolling back key elements of its nuclear programme pending the negotiation within a year of a comprehensive agreement designed to prevent Tehran from achieving a nuclear “breakout capacity”, or the ability to build a bomb within a short period of time. That goal is widely considered to be the single - most important – and potentially dangerous, both politically and strategically — foreign policy challenge facing Obama in his second term. While Obama has pledged to use all means necessary, including taking military action, to prevent Tehran from obtaining a bomb, he has made little secret of his strong desire to avoid becoming engaged in yet another war in the Middle East, a desire that appears widely held both within the foreign policy and military elite, as well as the general public, according to recent opinion polls. For its part, Iran has long said it has no intention of building a bomb. But it has also insisted that any final agreement must recognise its “right” under the Non - Proliferation Treaty(NPT) to enrich uranium to levels consistent with the needs of a civil nuclear programme. While the administration and the other P5 + 1 powers appear inclined to accept a deal that would, among other things, permit limited enrichment under an enhanced inspection regime, Israeli Prime Minister Benjamin Netanyahu has demanded that any final accord should effectively dismantle Iran’s nuclear programme, including its enrichment capabilities. Netanyahu’s demands are largely reflected in the pending Senate bill which is named for its co - sponsors, Republican Sen. MarkKirkand DemocraticSen. Robert Menendez,each of whom receivedmore campaign money from AIPAC - related political - action committees than any other senatorial candidates during their runs for office – in 2010 and 2012, respectively. The bill would impose sweeping new sanctions against Tehran if it fails either to comply with the terms of the Nov. 24 accord or reach a comprehensive accord within one year. Such sanctions would also take effect if Iran conducts a test for ballistic missiles with a range exceeding 500 kms or if it is found to have directly or by proxy supported a terrorist attack against U.S. individuals or property.