This is a rush transcript from "On the Record ," April 28, 2009. This copy may not be in its final form and may be updated.

GRETA VAN SUSTEREN, FOX NEWS HOST: There is bombshell political news here in Washington, D.C. This political town is really rocking. Long-time Republican Senator Arlen Specter is saying adios to the Republican Party. He's switching to the Democratic Party.

Senator Rick Santorum is here with us. Nice to see you, Senator.

RICK SANTORUM (R-PA), FORMER SENATOR: Thank you, Greta. Good to be with you.

VAN SUSTEREN: And both of you -- well, he is a Republican senator from -- or maybe Democratic senator from the state of Pennsylvania, but you were a Republican senator from the state of Pennsylvania.

SANTORUM: I was. We were colleagues for 12 years. I served 12 years with him in the Senate. And he -- I got a call first thing this morning, and I looked that I got a call from Senator Specter, and I -- I'm doing -- I'm hosting a radio show, and there were a lot of calls about Senator Specter this morning on the radio show that I'm hosting. I'm filling in Bill Bennett. And I thought, Oh, he's calling me because I didn't stand behind him and I sort of said I'm going to sit on the sidelines. And I thought, Oh, I'm not going to return this call. He's just going to chew me out.

So I waited an hour. And I got a call from John Cornyn, who's the chairman of the Republican senatorial committee. He said, Is it true? I said, What's true? Did Arlen call you? I said, yes, he called me. He said, Well, did he say? I said, Well, I haven't called him back. He said, Well, call him back because we're worried he's going to switch.

And I called him back, and he admitted it to me. He said, you know, I'm calling you because I want to let you know beforehand, before it leaks out, that I'm going to switch. And he laid it out very clearly. Arlen is a very transparent guy, in my opinion. And what he said was, Look, this is the only way I can win and I can't win any other way and...

VAN SUSTEREN: Is that true?

SANTORUM: Yes. I think that's probably true, at this point. You know, he told me -- and I know. I've gotten the feedback from people I've talked to in Pennsylvania. He's been traveling around the state, talking to Republican leaders, talking to, you know, the money people as to where they're going to be and what they're going to do. And I think he's figured out that the vote that he cast against -- against the party and against the movement, cutting the deal with Obama to get his -- you know, his largest expansion of government in the history of this country passed, was the straw that broke the camel's back. It's way out of line for where the average Republican is.

We can -- you know, depending on where you are on the spectrum, you can forgive Arlen for a lot of different things, but this -- this, you know, dramatic, fundamental change in the role of government in people's lives, which I think Obama did here in this first foray, was an offense to every Republican, and that broke the back.

VAN SUSTEREN: Is it that he can't win? He has a Republican challenger, or would if he were still a Republican, in the state of Pennsylvania. Is it that he couldn't win the primary...

SANTORUM: Right.

Watch Greta's interview with Rick Santorum

VAN SUSTEREN: ... but that he can win in a general election? I mean, when everyone's called to sort of vote, he can win. It's just that he can't win with his own party.

SANTORUM: Yes, he can't win with his own party. And I think prior to that vote, he actually could have won with his own party. I'm not even sure that Pat Toomey, who is the person that he was losing to in these polls that he was taking, would have -- would have even gotten in the race. He was actually running for governor.

But Arlen not only, you know, stuck his chin out, he stuck his rear out, and then he pulled his pants down and wiggled it at us. And that was just enough, and people just said, Enough. Pat figured it out and got in the race.

And now the interesting question is, is who else is going to get in the race. I mean, I'm not too sure that Pat may be the only candidate. I think there are other people looking at it. And you know, we're -- it's going to be an interesting time in politics in Pennsylvania. But I think the more important issue, candidly, is -- you know, the impact here in this town is huge. I mean, we're looking at 60 votes for the Democrats, assuming Al Franken...

VAN SUSTEREN: But he says he's not going to vote any differently. Do you believe that?

SANTORUM: Look, I worked Arlen Specter. I was in the leadership for six years, and I worked Arlen. I -- Arlen was my guy. I mean, that's when -- when Bill Frist or Trent Lott were the leaders, if they needed Arlen, they came to me and said, you know, We need your help. And I know how many times Arlen voted with us when he really didn't want to vote with us. Well, now it's going to be easy not to vote with us.

And there'll be times -- because I know the other side, and they are 10 times heavier-handed than we are on the Republican side because I know that, having talked to former Democratic senators who came over to us, and they were always amazed at how easy -- how soft-glove we were on our side.

They're going to hammer him hard. Sixty is important to them. There are big issues that they want to accomplish. They know they've got a two- year window, potentially, and only a two-year window, to get major, major big government programs passed that, in my opinion, Arlen in his heart does not necessarily disagree with. And so I think that while he wants to show his independence, and he will on some issues, Arlen will be a very good vote for them over the long term, and that 60 will be a real 60.

VAN SUSTEREN: All right, if I want to listen to you tomorrow on the radio, what time?

SANTORUM: I'm on at 6:00 -- from 6:00 to 9:00 in the morning on Bill Bennett's "Morning in America." Tune in and you'll hear more analysis, I guess.

VAN SUSTEREN: All right, more -- more from the senator tomorrow at 6:00 AM. That's very early. Senator, thank you very much.



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