Sen. Ben Cardin (D-Md.) said Sunday that Congress won't allow the temporary deal on Iran's nuclear program to become the final deal.
Cardin suggested on "Fox News Sunday" that the final agreement must be tougher.
"That would not be acceptable to the Congress not the American people and I hope the international community," Cardin said. "We will not stand by and let this be the final deal."
The agreement reached early Sunday in Geneva is being pitched as a first step in broader negotiations about Iran's nuclear program. It halts installation of new centrifuges for enriching uranium and restricts how and how much Iran can enrich uranium.
Cardin expressed skepticism that Iran would meet its obligations.
"We are very concerned as to whether Iran will live up to even this commitments, and this is a first step," Cardin said.
Appearing on the same program, GOP Sen. Bob Corker (Tenn.) suggested senators may still look at additional sanctions -- sanctions that would likely torpedo the temporary deal.
"I think there are going to be some people that want to [propose] additional sanctions," Corker said. "That’s another effort that we may well take part in."
Corker is working on legislation that would protect existing sanctions as the short-term deal is instituted.