Officials in key parts of the Obama administration are increasingly convinced that sanctions will not deter Tehran from pursuing its nuclear program and believe that the U.S. will be left with no option but to launch an attack on Iran or watch Israel do so, the British Guardian reported on Friday.

According to the report, despite the fact that President Barack Obama has made it clear that he is determined to give sufficient time for measures such as the financial blockade and the looming European oil embargo, there is a strong current of opinion within the administration – including in the Pentagon and the State Department – that believes sanctions are doomed to fail, and that their principal use now is in delaying Israeli military action.

An official who is knowledgeable on Middle East policy told the Guardian, “The White House wants to see sanctions work. This is not the Bush White House. It does not need another conflict. Its problem is that the guys in Tehran are behaving like sanctions don’t matter, like their economy isn’t collapsing, like Israel isn’t going to do anything.”

The official added, “Sanctions are all we’ve got to throw at the problem. If they fail then it’s hard to see how we don’t move to the ‘in extremis’ option.”

Another official told the newspaper that some members in the administration “don’t see a way forward,” adding that “the record shows that there is nothing to work with.”

The Guardian said that if Obama concludes that there is no choice but to attack Iran, he is unlikely to order such an attack before the presidential election in November unless there is an urgent reason to do so. The question which remains, the report noted, is whether the Israelis will hold back that long.

U.S. Defense Secretary Leon Panetta said earlier this week he does not think Israel has made a decision to launch a military strike on Iran to thwart its nuclear ambitions.

Earlier this month, however, Panetta told the Washington Post that he thought the window for an Israeli attack on Iran is between April and June.

Colin Kahl, who was U.S. deputy assistant secretary of defense for the Middle East until December, told the Guardian, “With the European oil embargo and U.S. sanctions on the central bank, the Israelis probably have to give some time now to let those crippling sanctions play out.

“If you look at the calendar,” he added, “it doesn’t make much sense that the Israelis would jump the gun. They probably need to provide a decent interval for those sanctions to be perceived as failing, because they care about whether an Israeli strike would be seen as philosophically legitimate; that is, as only having happened after other options were exhausted. So I think that will push them a little further into 2012.”

Kahl said part of Washington’s calculation is to judge whether Israel is seriously contemplating attacking Iran, or is using the threat to pressure the U.S. and Europe into confronting Tehran.

“It’s not that the Israelis believe the Iranians are on the brink of a bomb,” he said. “It’s that the Israelis may fear that the Iranian program is on the brink of becoming out of reach of an Israeli military strike, which means it creates a ‘now-or-never’ moment.”

On Friday, polls produced by the Gallup Institute and the Pew Research Center revealed that 58 percent of Americans support using force to prevent Iran from getting nukes.

When it came to the question of supporting an Israeli attack on Iran’s nuclear program, 62 percent of the Republicans favored such support as compared with 33 percent for Democrats and Independents.