On NRO today, I interviewed Rick Santorum about his endorsement of Mitt Romney and his thoughts on his former Senate colleague John McCain’s presidential campaign. Consistent with his past statements, Santorum was highly critical of McCain. Today McCain responded directly to Santorum’s criticism during an interview with Katie Couric:

KATIE COURIC: Let me first start by asking you, Sen. McCain, about some news of the day, if you will. Sen. Rick Santorum, who has endorsed MittRomney, has done automated call for the Romney campaign telling voters, quote, “As a conservative I don’t agree with McCain on many issues. And I don’t think he has the temperament and leadership ability to move the country in the right direction.” What do you think about Rick Santorum’s use of the word temperament and this automated call? JOHN MCCAIN: Well, I’m just pleased and grateful that I have the support of so many senators who are still in the Senate. Ranging from the most conservative, Tom Coburn, to Trent Lott, to Richard Burr and Lindsay Graham. To all of those. And the governors of the three largest states that we have as Republican governors: Charlie Crist, Arnold Schwarzenegger. Now Rick Perry in Texas. And now, former governor [George] Pataki. I’m very grateful for the support that I have from so many elected officials. Including Jack Kemp and Phil Graham and so many others. And people I served with in the senate as well. COURIC: Having said that, Sen. McCain, the temperament question has come up … at different times during the course of the campaign. Rick Santorum said he had witnessed problems with your temperament, which he declined to detail. And he said, quote, “I don’t know anybody in the senate who hasn’t. Everybody has their McCain story.” What’s your reaction to that? MCCAIN: Again … I don’t know what a defeated candidate for reelection who begged me to come up and campaign for him has to say. But I know what my other colleagues, those who I have served with, and those that I am serving with. So many of them who are supporting. More than anybody else.