US AND IRAN LOCKED IN GAME OF NUCLEAR CHICKEN

The U.S. is one of six nations at the table with Iran in Vienna, but the nuclear talks are shaping up to be a high-stakes game of chicken between Washington and Tehran.

The question is, who will blink first? Many would argue it's the one who wants the deal more.

One common narrative is that Secretary of State John Kerry, enchanted with his budding relationship with Iranian Foreign Minister Mohammad Javad Zarif and desperate to cement his place in history, will become wobbly and give the Iranians too many concessions in a final agreement.

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It's a narrative Kerry aides firmly reject, insisting Kerry has several times threatened to walk away from the table. It also reflects a lack of understanding about the way negotiations of this nature work. While as lead negotiator Kerry may decide tactics, he can't ultimately can't cross red lines set by President Barack Obama, any more than Zairf or Iranian President Hassan Rouhani can cross the red lines set by Ayatollah Ali Khamenei, Iran's supreme leader.

Obama, too, badly wants a deal. He also has a legacy to firm up. And without an agreement, he faces the possibility that his final 15 months in office will feature the threat of an accelerated Iranian nuclear program, a breakdown of the sanctions regime and tensions with Israel -- even the remote possibility of an Israeli military strike. What's more, Iran could also act out more in the region, increasing its antagonism of U.S. allies.

Obama's tough comments

But is Obama so desperate for a deal that he is willing to make concessions that abandon the basic parameters he laid out and open him up to critics' accusations of capitulation?

His comments during a press conference Friday, in which he said there would not be a deal unless it verifiably cut all pathways to an Iranian nuclear weapon, suggest he intends to hang tough.

The Supreme Leader, for his part, laid out some pretty tough red lines himself in a speech last week. His seven demands, re-posted on Twitter, included a shorter duration for a deal and its restrictions on Iranian nuclear research, immediate removal of economic sanctions once a deal is hatched and the banning of inspections at Iranian military sites. All seemed contrary to the political framework agreed to in April in Lausanne, Switzerland.