The Obama administration�s effort to reach a final nuclear agreement with Iran is expected to slip past its deadline�Tuesday, though U.S. officials expressed confidence a deal is within reach.

�At this point, I would anticipate the negotiations will extend past the deadline,� White House press secretary Josh Earnest told reporters�Monday.
�Our negotiators will remain in Vienna past the deadline in pursuit of a final agreement.�

Earnest declined to handicap the chances of reaching a deal, but said a final agreement "is within our sights."

�I would hesitate to put numbers on it at this point,� he said. �Obviously our negotiators understand the stakes in the negotiations.�

The administration previously aimed to have a final agreement completed by�June 30, capping off a nearly two-year effort to curb Iran�s nuclear program.

The U.S. and five other world powers are finalizing technical language on a framework deal, reached in April, that would place limits on Teheran�s nuclear capabilities to prevent it from building a weapon in exchange for international sanctions relief.

But negotiators meeting in Vienna have faced several last-minute stumbling blocks, including the pace of sanctions relief and the scope of inspections on Iran�s nuclear sites.

Complicating the already tense talks was the decision by Iran�s chief negotiator, Foreign Minister Mohammad Javad Zarif, to return home � possibly to discuss the parameters for a final deal with Iran�s leaders.

Zarif is expected to return to Vienna�on Tuesday.

Earnest said U.S. negotiators are willing to talk for a few more days but reiterated President Obama would be willing to walk away from a deal that does not close off Iran�s path to a nuclear bomb or force it to submit to �intrusive� inspections.

�If the Iranians refuse to agree to a final agreement that is consistent with the framework that was reached in April, then there won�t be an agreement,� Earnest said.

He noted the lapse is not unusual. Talks over a preliminary agreement were slated to end�March 31 but instead were completed on�April 2.

It is unclear how much longer the talks will last, but observers see�July 9�as the real cutoff date to strike a deal.

If an agreement is presented to Congress before�July 9, lawmakers will have only 30 days to review it before Obama can begin lifting sanctions on Iran imposed by Congress, under a bill passed in May.

But if it is filed after, the review period jumps to 60 days.

Supporters of the deal fear that a longer review process could allow opponents more time to mobilize to kill the deal in Congress.

�That would be a very negative scenario for both sides,� Trita Parsi, president of the National Iranian American Council, told The Hill. �There is an awareness the longer the process is, the opposition to the deal would have the chance to chip away senators from the president�s side.�

If Obama must wait longer for Congress, that increases the odds that regional conflicts in the Middle East could complicate the review, said Parsi, who is in Vienna for the talks.

A conflict in Yemen, which has pitted Iranian-backed Shiite rebels against the U.S.-backed government cast a pall over talks on a preliminary agreement in March, although the deal was eventually sealed.

The White House already faces a tough task in selling the deal to skeptical members of Congress. Top Republican senators, and some Democrats, are raising pressure on the administration by signaling they intend to try to stop the agreement.

Senate Foreign Relations Committee Chairman Bob Corker (R-Tenn.) sent a scathing letter to Obama earlier this month, saying the U.S. has made �breathtaking� concessions to Iran that could lead to a �bad deal.�

�The people around the president see this as such a legacy issue,� Corker told USA Today�on Sunday.� There�s a great concern from people on both sides of the aisle that they are willing to cross some lines that should not be crossed just to get a deal.�

Corker expressed concern United Nations inspectors won�t have access to Iranian military sites where nuclear activity has been suspected and that the world powers will not demand Teheran fully detail its past nuclear efforts.

Those demands are crucial to verifying Iran�s claim that its nuclear program is for peaceful purposes only, lawmakers say.

Those concerns were heightened when Iran�s Supreme Leader Ayatollah Ali Khamenei said last week he would not allow inspections of military sites allegedly involved with the country�s nuclear program.

He also demanded the U.S. and its negotiating partners � the United Kingdom, France, Germany, Russia and China � lift all sanctions immediately after the deal is reached.

A senior U.S. official said�Monday�that negotiators offered language that would allow�the International Atomic Energy Agency, the U.N.�s nuclear watchdog, to inspect�all sites in Iran suspected of nuclear activity, including military installations. But not all of Iran�s military facilities may be open to inspectors.

�We have worked out a process that we believe will ensure that the IAEA has the access it needs,� the administration official told reporters in Vienna. �The entry point isn't, we must be able to get into every military site, because the United States of America wouldn't allow anybody to get into every military site, so that's not appropriate.�

Iran�s negotiating partners have demanded that sanctions relief be gradually implemented as inspectors verify Tehran is abiding by the terms of the agreement. The U.S. also wants sanctions to be able to be �snapped back� if Iran violates the deal.

But opponents worry sanctions won�t be easily snapped back. There�s some internal tension among the negotiating partners over reimposing economic penalties. Russia and China, who are veto-wielding members of the U.N. Security Council, are eager to do business with Tehran.

Even if Iran is found to violate the deal, it could be difficult to get all countries to agree to bring back sanctions.

�There is an inherent asymmetry in the deal between an Iranian nuclear program that expands over time and Western economic leverage that diminishes over time,� Mark Dubowitz, executive director of the Foundation of Defense of Democracies, told The Hill.

�The problem is, it will be like a slow motion train wreck,� he added. �It won�t be obvious the train is crashing.�

By The Hill