[cnn-photo-caption image= http://i2.cdn.turner.com/cnn/2008/POLITICS/08/14/warren.forum/art.warren.sitroom%20copy.jpg caption= "The Rev. Rick Warren appears on The Situation Room Thursday"]
WASHINGTON (CNN) - The Rev. Rick Warren said Thursday that his upcoming forum with Sens. John McCain and Barack Obama will be aimed at asking them tough "heartland questions."
The author of the best-selling book "The Purpose-Driven Life" is to interview McCain and Obama on Saturday.
The candidates will appear together at Warren's 20,000-member Saddleback mega-church in southern California.
"Well, I'm a pastor, not a pundit," he told CNN's Suzanne Malveaux on Thursday's "Situation Room." "One of the things we're going to do is I'm going to ask identical questions to both candidates, which will be different.
"I'm not going to play 'gotcha' with one candidate and not with the other. This way, it will be totally fair. You compare apples to apples," he added.