Republicans are about evenly divided on an Iran deal, with 47 percent in support and 43 percent opposed. The split contrasts with Republican lawmakers’ widespread backing of Israeli Prime Minister Benjamin Netanyahu’s speech deriding the potential deal in early March before a joint session of lawmakers. Additionally, all but seven Republican senators signed a letter to Iran’s leadership warning that Congress or a future president could override any agreement made by the Obama administration.
So now Iran has a letter from some senators stating that Congress or the next president can "override" any agreements.
Makes me wonder what could happen before election day 2016, ya know?