WASHINGTON – Among the beltway press and in our heady politics, how to proceed with Iran is a fierce topic deep in the weeds. How best can the US government demonstrate its seriousness at the negotiating table? Do we sanction Tehran now, later, or pass sanctions now punishing them later? Equally important: Which option upholds US standing abroad? Will sanctions strengthen the position of UN Security Council members in their talks with Iran over its nuclear program? Or will America become the spoiler – sabotaging the talks in their eleventh hour, responsible for the consequences?US President Barack Obama has made clear that, after a year of negotiations, his diplomatic team has determined that a new sanctions bill from Congress would “guarantee that diplomacy fails;” alienate the US from its allies; and prompt the resumption of Iran’s nuclear work.Members of Congress disagree. Keen to play a role, they have twice now drafted a bill that would trigger sanctions against Iran only after diplomacy breaks down without a deal.While the bill would become “enacted” US law, sanctions themselves would not be “imposed” – an action prohibited by an interim deal, the Joint Plan of Action, framing the nuclear talks.“The US administration, acting consistent with the respective roles of the president and the Congress, will refrain from imposing new nuclear-related sanctions,” the agreement reads.None of this matters.Because the president has made his choice: He will veto new sanctions legislation.The bill has no realistic chance of becoming law.An initial vote on the Nuclear Weapon Free Iran Act of 2015 will earn bipartisan support; it was written by Democrat Sen. Bob Menendez of New Jersey, and Republican Sen. Mark Kirk of Illinois. The bill will be introduced with “balanced co-sponsorship,” one senior aide says.But with Obama and UK Prime Minister David Cameron making personal calls to Democratic senators, the vote count will be suppressed. The bill will almost surely pass, but not with the number of Democrats necessary to clinch more than 67 votes.That number matters because, should Republican leadership seek a second vote after the president vetoes the bill, 67 votes are required to override his action.But asking Democrats to vote for a bill on Iran that the president opposes is an entirely different request from asking them to override a Democratic president’s veto.Historically, only four percent of all presidential vetoes have been overturned – and in the last fifty years, only one of those has related to foreign policy. Ronald Reagan vetoed a bill brought to a vote by his own party in the Senate in 1986 that sanctioned South Africa for apartheid; a vote to overturn the veto codified the Comprehensive Anti-Apartheid Act in October, three months after it was originally introduced.Everything in Washington takes time, and the bill introduced this week will likely first get a vote in mid-February, after Prime Minister Benjamin Netanyahu addresses Congress on the matter.Deadline for a political framework agreement between negotiating powers is only a month later, in late March.Given the time frame, the history and political pressure on Democrats not to buck their president, it would be a shocking turn of events to see a bill truly act as subterfuge in these negotiations.Iran would have to actively seek an exit from the talks in order to cast Congress’s mere passage of a bill, without Obama’s signature, as a violation of the terms.