WASHINGTON: America's top diplomat is plunging back into Iranian nuclear talks, keeping one eye on the longtime U.S. adversary and the other on political developments at home, as pressure rises in Washington for a deal ensuring the Islamic republic cannot become a nuclear state.
The prospect of a Republican takeover of the Senate means Secretary of State John Kerry will be on a tight leash with a late-November deadline approaching for an agreement.
Kerry, European Union negotiator Catherine Ashton and Iranian Foreign Minister Mohammad Javad Zarif will meet in Vienna next Wednesday, the EU said.
Another negotiating round is expected shortly after to include Britain, China, France, Germany and Russia.
There are seven weeks to seal a comprehensive accord easing economic penalties against Iran in exchange for curbs on its nuclear program. Failure could mean the process has fallen apart.
Iran has invested billions and says it won't dismantle a program of energy production that it considers its inherent right.
Hawks in the U.S., Israel and elsewhere worry that too many concessions are being offered, leaving Iran on the threshold of developing nuclear weapons and destabilizing the Middle East and beyond.
U.S. and European negotiators hope that capping Iran's uranium centrifuges at a few thousand would force Tehran to redesign a potential plutonium plant. They also want strict inspections of Iranian sites to be part of a solution.
The diplomats aren't simply negotiating with one another.
Iran's moderate-leaning president, Hassan Rouhani, must sell any deal to hard-liners at home and win the blessing of Ayatollah Ali Khamenei, who has been ambiguous about his support for nuclear diplomacy.
President Barack Obama must do likewise with Congress.
For Iran, the fear is that the benchmarks of any understanding with the U.S. could shift once a plan is presented to American lawmakers. That possibility becomes more likely if Republicans take the Senate majority in next month's elections.
Rouhani gave an optimistic assessment of the talks Wednesday, saying that only details separate the two sides. But dissidents accused his government of secretly moving sensitive research facilities to hide them from the West.
The pressure on the Obama administration was once bipartisan; now it is more divisive.
Republicans are impatient with the lack of progress a year after an interim agreement with Iran that many of them opposed. They've tried to attach Iran legislation to unrelated Senate bills, only to be rebuffed by Democratic leaders.
Democrats are avoiding a fight, for now.
Several Democratic aides, who weren't authorized to speak publicly on the matter and demanded anonymity, said part of the shift in their thinking reflects an understanding that the "good cop, bad cop" approach the administration and Congress had used as a form of leverage with the Iranians may no longer be helpful.
If the Iranians are convinced that Obama can't deliver a permanent deal sealed by Congress, they have less incentive to permanently roll back uranium and plutonium programs to levels demanded by world powers. Obama will be out of office in January 2017. Without congressional action, his temporary steps to ease financial pressure on Iran can be quickly reversed then.
In discussions with the Iranians, diplomats say, American officials have played down suggestions U.S. lawmakers could scuttle a deal. But Congress can prevent Obama from making the exchange more far-reaching, something the Iranians are almost surely taking into account at the negotiating table.
Nearly all U.S. sanction provisions on Iran allow for presidential waivers. Any penalties introduced through executive orders by Obama or previous presidents can be replaced by new orders. Also, the executive branch has flexibility over how it chooses to enforce them.
But the president needs cooperation with Congress to permanently void any of the wide-ranging U.S. sanction laws in place against Iran.