KARL: Let's straight to the GOP front-runner, Donald Trump, who joins us by the phone. Sir, thank you for joining us. DONALD TRUMP, ENTREPRENEUR: Thank you, Jon. KARL: So I want to get to the debate in a moment. But we have this news this morning that Joe Biden is looking into running. What's your assessment? Would he be harder to beat than Hillary Clinton? TRUMP: Well, I think it's a real possibility because what she did was absolutely, in my opinion, illegal and I don't think she's going to be allowed to run if they have a prosecutor who's going to be honorable because if you look at Gen.