World leaders have been gathered in Lausanne, Switzerland for weeks trying to hammer out a deal on the future of Iran's nuclear program. Today, their ranks shrunk by one: Russian Foreign Minister Sergei Lavrov announced he was leaving for Moscow Monday afternoon, less than 24 hours before the deal's Tuesday deadline.

Lavrov's abrupt departure is a sign that negotiations are not going so well, said Charles Sennott, cofounder of GlobalPost and head of The GroundTruth Project.

"If Lavrov is leaving the talks, it's an indication this thing is going into pause mode," he said.

A spokeswoman for Lavrov stressed that the foreign minister could return to Switzerland at any time if a deal appears imminent. But Sennott said the negotiations may already have been thrown into jeopardy.

"They could probably hit another restart, but that would be a real setback," he said. "I don't think you're going to hit a point where it just breaks off. I think they'll hit a very depressing reality they were not be able to get a deal together. They'll all have to go back, and it will take more time."

If a deal does move forward, Sennott pointed out it may face an upward political climb in the United States. Earlier this month, 47 Republican Congressmen wrote an open letter to Iranian leaders warning that any deal could be undone by future administrations.

"It's going to be intensely bitter partisan politics circulating around the Iran deal. If there is a deal cut, it's not anywhere near over in terms of how it plays out politically in the United States," he said.

To hear more from Charles Sennott—including his take on his recent trip to Myanmar—tune in to Boston Public Radio above.