Iranian Supreme Leader Ayatollah Ali Khamenei, seen here in a photo released by his official website Thursday, stopped short of giving his endorsement to the framework nuclear deal struck last week. AP hide caption

itoggle caption AP

President Obama speaks to NPR's Steve Inskeep at the White House on Monday. The president is pressing hard for a full-fledged nuclear agreement with Iran, part of his outreach to states that previous presidents ostracized for decades. Maggie Starbard/NPR hide caption

itoggle caption Maggie Starbard/NPR

Iranian oil workers gather at an oil refinery south of the capital Tehran, Dec. 22, 2014. Iran's oil exports have been crippled by sanctions. Vahid Salemi/AP hide caption

itoggle caption Vahid Salemi/AP

Iranian Foreign Minister Javad Zarif (right) delivers a statement, flanked by European Union High Representative for Foreign Affairs and Security Policy Federica Mogherini. Brendan Smialowski/AFP/Getty Images hide caption

itoggle caption Brendan Smialowski/AFP/Getty Images

Houthi fighters gather in the Yemeni city of Aden on Thursday. The Shiite rebels and their allies seized the presidential palace in this southern coastal city. Wael Qubady/AP hide caption

itoggle caption Wael Qubady/AP

Ahead of Tuesday's deadline, Secretary of State John Kerry, Russian Foreign Minister Sergei Lavrov, German Foreign Minister Frank-Walter Steinmeier, French Foreign Minister Laurent Fabius and Chinese Foreign Minister Wang Yi wait Monday for the opening of a plenary session on Iran's nuclear program at the Beau-Rivage Palace Hotel in Lausanne, Switzerland. Fabrice Coffrini/AFP/Getty Images hide caption

itoggle caption Fabrice Coffrini/AFP/Getty Images

David Petraeus speaks in Los Angeles on Nov. 7, 2014. The former head of the U.S.-led coalition in Iraq tells The Washington Post that Iran and Shiite-backed militias pose a greater threat to Iraq than the self-described Islamic State. Imeh Akpanudosen/Getty Images hide caption

itoggle caption Imeh Akpanudosen/Getty Images

Shiite fighters and Sunni fighters, who have joined Shiite militia groups known collectively as Hashid Shaabi ("Popular Mobilization") to fight the Islamic State, gesture Tuesday next to former Iraqi President Saddam Hussein's palaces in the Iraqi town of Ouja, near Tikrit. Thaier Al-Sudani/Reuters/Landov hide caption

itoggle caption Thaier Al-Sudani/Reuters/Landov

U.S. Secretary of State John Kerry speaks at a news conference in Sharm el-Sheikh, Egypt, on Saturday. Kerry said he's returning to nuclear negotiations with Iran with "important gaps" standing in the way of a deal. Brian Snyder/AP hide caption

itoggle caption Brian Snyder/AP

Its doubtful that Arkansas Sen. Tom Cotton (right) will face legal consequences for the letter he wrote to Iran. The Logan Act hasn't been used to prosecute anyone since it was passed more than 200 years ago. Lauren Victoria Burke/AP hide caption

itoggle caption Lauren Victoria Burke/AP

A letter from U.S. senators suggests the lawmakers "not only do not understand international law, but are not fully cognizant of the nuances of their own Constitution," says Iranian Foreign Minister Mohammad Javad Zarif. Kyodo /Landov hide caption

itoggle caption Kyodo /Landov