If the next president wants to attack Iran to stop it from building a nuclear weapon, Congress seems unlikely to stand in the way.

Overwhelming majorities in both chambers are on record in support of a policy that rules out containment of a nuclear-armed Iran as an option. And lawmakers, including Sen. Lindsey Graham, are eyeing new resolutions that would back Israel if it attacks and, potentially next year, authorize the use of U.S. military force.

“The Congress is ready to do what is necessary to support military intervention if sanctions don’t work,” the South Carolina Republican predicted in an interview last week.

Graham said there is broad agreement in the Senate that Iran must be stopped from developing a nuclear weapon. “The 30,000-foot view of Iran is very bipartisan: This regime is crazy, they’re up to no good, they are a cancer spreading in the Mideast. … Almost all of the Democrats and Republicans buy into the idea that we can’t give them a nuclear capability,” he said.

Both President Barack Obama and Republican presidential nominee Mitt Romney have rattled sabers about possible military action if Iran continues to move toward nuclear capability. Obama warned members of the United Nations last month that the window of time available to negotiate a solution and avoid military action was shrinking.

And both Obama and Romney have forcefully ruled out containment, or adapting U.S. policy to the inevitability of a nuclear-armed Iran.

The House adopted an anti-containment resolution on a 401-11 vote in May. The Senate passed a similar resolution sponsored by Graham, 90-1, last month in an after-midnight vote  Senators cast before heading home for the elections. Graham’s measure had 83 co-sponsors.

The lead sponsors of the Congressional resolutions have made clear they prefer tough sanctions to a military solution, and some Senators have issued statements filled with caveats. But Graham said the logical outcome if sanctions fail would be a pre-emptive strike.

While his resolution explicitly stated it was not an authorization of military force, Graham said it could lead to one next year.  “If a president came to us and said that sanctions are not working and they are on the verge of a breakout … I think there would be an overwhelming vote to authorize force,” he said.

Graham suggested that the next president give the Iranians a firm timeline to reach a deal or face the prospect of an attack.

And while the Senator said he does not believe the president would need Congressional authorization to launch an attack,  Congressional passage of an authorization next year would put more pressure on Iran to yield to a final diplomatic push.

Sanctions have had a major effect in recent months, with the value of the Iranian currency plunging and prices soaring. But it is not clear if that will yield a solution to the crisis.

In the meantime, Graham said he is working on a new resolution he will introduce after the elections to promise Israel  U.S. economic, diplomatic and military assistance if it attacks Iran first.

Graham noted that Obama has told Israelis he has their back and said his resolution would put that statement into action. Graham said that to him, having someone’s back means, “If you get in a fight, I’m coming to help you.”

So far, voices against a military commitment have been muted, with the notable exception of Sen. Rand Paul (R-Ky.), who cast the lone “no” vote on the anti-containment resolution. He ripped the measure, likening it to the prelude to the Iraq War. “A vote for this resolution is a vote for the concept of pre-emptive war,” Paul declared.

Senate Judiciary Chairman Patrick Leahy (D-Vt.) issued a statement as he voted for Graham’s resolution, noting that it was nonbinding and did not endorse military action. “The policy of the Administration, and of our allies is to support sanctions, to use diplomacy, to resort to military force only if all other options fail,” Leahy said.

Agreeing on whether “all other options” have failed could be the area that divides Congress next year if a use of force resolution is presented for votes.

Former Ambassador Dennis Ross, who served as a special assistant to Secretary of State Hillary Rodham Clinton focusing on Iran and is now counselor at the Washington Institute of Near East Policy, said several other steps would be pursued before any United States attack to halt Iran’s nuclear program.

Ross said the United States and the international community could offer to allow the Iranians to keep civilian nuclear power, with restrictions. Other carrots, along with sanctions, could help bring Iran to the table.

Still, “for prevention to not just be a slogan, ultimately you have to be prepared to act, including militarily,” Ross said.

Congress would also want to understand the potential consequences and plan for after an attack, he said.

But Ross said that, unlike the period before the U.S. invasion of Iraq, international watchdogs are warning about Iran’s growing nuclear capabilities, rather than raising questions. “You don’t have people saying we really don’t believe the threat,” he said.

One senior Democratic House aide agreed that Iran is different from the buildup to Iraq because there is no dispute that they have a growing nuclear capability.

“It will come down to what military and intelligence officials have to say and what they think is the best course of action,” the aide said. “They will have to lay out a compelling case.”