Transcript for Lindsey Graham: ISIS Would Kill 'Every Christian and Jew and Vegetarian In Their Way'

buzz board. At the top, the man once called America's mayor. Rudy Giuliani exploding the internet by saying he doesn't believe president Obama loves America. Doubling down on some fiery speeches. That's man who fights for his people, unlike our president! And taking on those who call his attack racist. I thought that was a joke, he told "The New York times" since Obama was brought up by a white mother. Jeb bush used his first foreign policy speech to declare his Independence. I love my brother. I love my dad. But I'm my own man. But his foreign policy team stocked with people from his father and brother's white house. Which brings us to our latest contender. South Carolina senator Lindsey graham is a long shot. He's holding his own in his home state. On Facebook, too. And on his first trek to Iowa this week, he made this pledge. This campaign is going to be fun. It's going to be challenging. We're going to give honest answers to hard questions. And senator graham joins us now. Thank you for joining us. Honest answers to tough questions. Do you think you can win the republican nomination? I don't know. But I'm going to give it a try. I think I can win south Carolina. I wouldn't be talking to you, first, step into Iowa was very positive. The way a guy like me would win is to offer a form of conservatism that would be able to grow the party and be able to be commander in chief on day one. The one thing I can tell anybody in Iowa, New Hampshire, anyone throughout the country, if I got to be president of the United States, I think I could create a pathway to straighten out the mess we're in. And we'll see where that goes. How about Rudy Giuliani? Was he right to question the president's love of America? I love Rudy. I don't want to go there. The nation's very divided. President Obama has divided us more than he's brought us together. And I don't want to add to that division. I have no doubt that he loves his country. I have no doubt that he's a patriot. But his primary job as president of the United States is to defend his country. He's failing miserably. And you have said in this came Pai-- campaign, one goals is to reset the table in foreign policy. Did Jeb bush do that in his foreign policy speech this week? Was anything missing ? I think he gave a speech consistent with sort of the traditional view of the republican party. The one thing we have to embrace as republicans is not just enough to criticize president Obama. What would we do differently? Isil is a direct result of bad policy choices, not leaving troops behind in Iraq. Not dealing with Syria three years ago. Through a no-fly zone. At the end of the day, I want the republican party to talk openly about the hard things, like having boots on the ground in Syria and Iraq, American boots on the ground as part of an international force to make sure we degrade and destroy. No question you think that is necessary? There is no doubt in my mind militarily that we cannot succeed degrade and destroy isil without having an American component. The regional forces don't have the ability, in my view, our help. Special forces. Intelligence gathering. Embedded trainers at the battalion level, probably. 3,000 troops in Iraq is too many to be hostages. I think too few to get the job done. A question of what to do here in the homeland. You heard secretary Johnson say he was frustrated by the house and the senate on the issue of funding. For the department of homeland security. Is this going to get resolved? Yes, it will. I agree with the Texas judge who said the executive orders were illegal. I hope republicans will come together and the court case. File a friend of the court brief with the court and fund dhs. I'm willing and ready to pass a dhs funding bill and let this play out in court. The worst possible outcome for this nation is to defund the department of homeland security given the multiple threats we face to our homeland. I won't be part of that. You won't be. But can you get it through the house? Time will tell. I hope my house colleagues will understand that our best bet is to challenge this in court. That if we don't fund the department of homeland security we'll get blamed as a party. And to anyone who is watching the world as it is, I have never seen more terrorist organizations, safe havens, more money, more capability to strike the homeland than I do today. That's a direct result of a failed foreign policy by president Obama. And the worst thing to do is to add gasoline to the fire by having the republican party defund the department of homeland security. One final question about the potential presidential run. Polling this week. You're leading the pack in south Carolina. They also ask, should you run for president? 58% of South Carolina registered voters said no. Why are the people who know you best weighing in against a run? Well, a lot of them are democrats, they probably don't want a republican running for president. At the end of the day, if I didn't think I could win my home state, I wouldn't be doing it. I'm trying to run a campaign, if I decide to run, that focuses on securing the nation. The pac is called security through strength. We have to have a forward-leaning presence. Lines of defenses over there. So the war doesn't come here. And when it comes to our $18 trillion national debt, somebody has to get republicans and democrats in a room and do what Ronald Reagan and tip o'neill did with our entitlement problems. Fix immigration. I'm willing to work with democrats. And when it comes to foreign policy, I have been more right than wrong the last three years. I have never been more worried about my country than I am today. In terms of radical Islam. And yes, it is radical Islam. The people in Iowa understood that. It's the source of the problem here. They've adopted a theory of religion that's 1,000 year old. That requires a worldwide call fa -- caliphate, that will purify the islamic religion, kill every Christian, Jew, or vegetarian in their way. They're not going to stop unless somebody stops them. We'll see you on the trail senator graham. Thank you.

This transcript has been automatically generated and may not be 100% accurate.