Most Republicans running for their party's nomination in the 2016 presidential election have been strongly opposed to the nuclear deal with Iran.
"Even former top Obama officials think emerging deal will ‘not prevent Iran from having a nuclear weapons capability’,” Former Florida Governor Jeb Bush tweeted last week. Included in his tweet was a link to a New York Times article about a letter from five former White House advisors expressing concern about the potential deal.
Florida Senator Marco Rubio was one of 47 Senate Republicans who signed a letter to Iran’s leaders earlier this year warning that any nuclear deal they reach with the Obama White House might not survive once he leaves the presidency in early 2017.
He had also pushed for an amendment requiring Iran to recognize the state of Israel as part of a bill that would let Congress weigh in on a nuclear deal with Iran. That and other controversial amendments that would have triggered a presidential veto were blocked or voted down and the legislation was approved.
Republican Senator Ted Cruz of Texas, who is also running for president, has said "Our first priority should be stopping a bad Iran deal that jeopardizes the lives of millions of Americans and millions of our allies."
Kentucky Senator Rand Paul split from most of his Republican colleagues and had spoken out in support of the engagement with Iran. “I think they need to keep the sanctions in place but I think keeping the door open, continuing conversations, is better than war,” Paul said earlier this year after launching his presidential bid. “I differ from some Republicans.”
On the Democratic side, frontrunner Hillary Clinton has been supportive of a nuclear agreement but has also warned about other issues with Iran.
"But even if we do get such a deal, we will still have major problems from Iran,” Clinton said last week. “They are the world’s chief sponsor of terrorism, they use proxies like Hezbollah to sow discord and create insurgencies to destabilize governments."