Exclusive: Sen. Tom Cotton responds to backlash over GOP letter to Iran

This is a rush transcript from "The Kelly File," March 10, 2015. This copy may not be in its final form and may be updated.

MEGYN KELLY, HOST: Joining me now, the man who drafted, signed and sent that letter, along with 46 other Republican senators, to the leaders of Iran. Republican Senator Tom Cotton who serves in the Armed Services Committee and is himself a veteran.

Senator, good to see you tonight. Let's start with the last bit, it's not just Howard Dean, it's not just Vice President Biden, the Wall Street Journal calling you out saying this is not helpful, and it sets the Republicans up to take a hit as being political beings on something that is important here, namely what happens with this deal with Iran.

SEN. TOM COTTON, R-ARK.: Well, on the contrary, Megyn, I think that this debate we're having is incredibly important, and helpful to raising just what a bad deal President Obama is about to make with Iran.

The last two days, we've focused on the terms of the deal, which is, one, President Obama will accept a 10-year sunset clause, and two, he's conceded a vast uranium enrichment capability to Iran. That paves the way for Iran to get the bomb as Prime Minister Netanyahu said last week. And the --


KELLY: But what's the point in writing to the Iranian mullahs? I mean, you know, like, what are you going to do? They dismissed it already like, whatever, and you've offended the Obama administration and you may have offended some of the Democrats who would have come over with the Republicans if -- depending on what happens with this deal -- to have a stronger say in the Senate.

COTTON: Megyn, if you talk to most Iran experts, they'll tell you that Iran's leaders don't understand our constitutional system. In fact, President Obama has said the president -- the Congress should not weigh in on this deal right now, even with future conditional sanctions, in part because it would confuse Iran's leadership.

So, we need to be crystal clear with the leaders of Iran. Any deal that's not approved by Congress won't be accepted by Congress. Not now, and certainly not in the future. Because Congress is focused on stopping Iran from getting a nuclear weapon, today, tomorrow, and 10 years from now.

KELLY: What do you say to those who say, you -- at a minimum, you've now alienated the Democrats, and that the -- the Republicans who you may need if you want to push through a sanctions package later on?

COTTON: Megyn, this is not about partisan politics, this is about stopping Iran from getting a bomb.

KELLY: Right. But --but -- but don't you need --

COTTON: I, too -- I, too, want to see --

KELLY: -- the Democrats if you want to do something contrary to what President Obama wants?

COTTON: I, too, want to see the bipartisan legislation pass that we've worked on in my committee, and that Senator Corker is working on in his committee. The president is the one who's weighing in the separation of powers, not a partisan matter, but a constitutional issue, and putting so much pressure on Democrats who share our viewpoint, regardless whether they sponsor a letter or signed a letter or sponsored legislation, the president doesn't want them to speak out and share their views that Iran cannot be allowed to get a nuclear weapon.

KELLY: But how is that -- I mean, listen --

COTTON: That's exactly what the president would do.


KELLY: -- you can make the case that President Obama has exceed his executive authority, right? I mean, many Republicans are making that case on many issues from immigration to ObamaCare right now. But discouraging the Democrats in the Senate from saying bad things about his deal isn't exactly an interference of separation of powers.

COTTON: We're -- we're encouraging the Democrats to join us, to protect Congress' constitutional responsibilities. The Founding Fathers insisted that Congress have the power to ensure that no president, whoever he or she may be, can make a binding international agreement, especially one about nuclear weapons, with the world's worst state sponsor of terrorism.

KELLY: What do you make of the fact that Joe Biden came out, the vice president said, this is beneath the dignity of an institution he reveres. He said he's offended by this. He says, you -- "it's designed to undercut a sitting president in the midst of sensitive international negotiations" and he went on to say he "cannot recall another instance in which senators have done this."

COTTON: For 36 years Joe Biden was a senator. He often weighed in, very eloquently, in defense of the Senate's prerogatives in protecting the United States from a bad deal. Now, I'm disappointed that senator -- or that Vice President Biden has changed this tune now that he's vice president. But his focus on the process just goes to show that he knows he can't defend the deal. But if he would like to defend the deal, I'd be happy to debate Vice President Biden one on one, anytime, the place of his choosing, maybe right here on your show, Megyn.


KELLY: You're more than welcome to do that. I hope he takes the invitation, the vice president.

Let me ask you about Representative Jared Polis of Colorado who sent out a tweet today. It looks like it may have been deleted since, calling you a man who served the country in uniform, "Tehran Tom." "Tehran Tom."

COTTON: Megyn, a few rhetorical bullets fired in a political debate don't really trouble me too much. What I'm focused on is Iran and stopping Iran from getting weapon and that's what 46 other senators are focused on and that's what the Congress is trying to stop the president from doing, negotiating a bad deal that would let Iran get the nuclear bomb.

KELLY: Do you think they're going to write you back?

COTTON: Well, Javad Zarif, the foreign minister of Iran, responded, and in his response, his ignorance of the American Constitution demonstrated the need for the letter to begin with.

KELLY: Did it start like, "Dear Tom, Hi! Thanks for your letter. Great catching up. By the way, forget everything you said, I'm talking to President Obama."

I got to go. Great to see you, Senator. Thanks for being here tonight.

COTTON: Thanks, Megyn.

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