Arkansas Sen. Tom Cotton charged that Iran will continue to violate international law even if a final nuclear agreement is reached.
"Unfortunately, Iran is an outlaw regime," the Republican said on CBS Sunday. "They're anti-American. They're terrorist-sponsoring."
"Just two days ago, two days ago, the supposedly moderate president of Iran, the kind of people that the [Obama] administration hopes to empower, was in the streets chanting, 'death to America' while people were burning American flags and Israeli flags," Cotton added.
Cotton also argued that the Obama administration has caved too much to Iranian leaders.
"Iran is destabilizing the Middle East in Iraq, in Syria, in Lebanon, in Yemen," he said. "They continue to be the world's worst sponsor of state terrorism."
"And by engaging in these negotiations, by granting these concessions to Iran, by not demanding, for instance, that Iran release immediately the four hostages that it holds who are American citizens, this administration has elevated Iran's role in the region," Cotton added.
Reports surfaced Sunday that a provisional deal meant to curb Iran's nuclear powers in exchange for sanctions relief was imminent. If one is not reached by Monday, it will be the fifth missed deadline since the original June 30 goal. If a deal is reached by July 13, Congress will have 60 days to review any final agreement.
Cotton, who sits on the Senate Committee on Foreign Affairs, has been one of the loudest critics on negotiating with Iran. In March, Cotton wrote a letter to Iranian leadership threatening that Congress would veto any unsatisfactory deal.