Tonight 8:00 to 10:00PM EST
WASHINGTON (CNN) -- The political spotlight will shine on Sens. John McCain and Barack Obama on Saturday night when the two candidates are expected to face tough questions on personal values, presidential leadership and international affairs.
The Rev. Rick Warren, author of the best-seller "The Purpose-Driven Life," will spend an hour interviewing each candidate at his 20,000-member Saddleback mega-church in Southern California.
On CNN's "The Situation Room" earlier this week, Warren said he won't play the role of a political pundit or ask "gotcha" questions, but rather tackle four areas of interest: the role of the presidency in government, leadership, the candidates' worldviews and America's role internationally.
The Saddleback Civil Forum on the Presidency will be carried on CNN TV and CNN.com/Live. It will be the last time the two candidates share the same stage before their parties' conventions. Three debates between the two are scheduled after the conventions.
Warren said he's focused on asking both presumptive nominees questions that "don't have a lot wiggle room.""But I do want to know how they handle a crisis, because a lot of the things in the presidency often deal with things you don't know are going to happen, that we don't know will happen in the next four years. ... There are a lot of different things you can deal with in the life of a leader that will tell us more about the candidate than some of the typical questions," he said.
Warren said he won't endorse either candidate and will let his followers make up their minds.
The stakes will be especially high for McCain, who has made a strong appeal this year to social conservatives and evangelical Christians.
A CNN/Opinion Research Corp. poll, taken July 27-29, showed that among white, born-again or evangelical voters, 67 percent are for McCain, with 24 percent for Obama.
Although it's a strong showing for McCain, he's lagging 11 percentage points behind President Bush in the 2004 election. Exit polls show that Bush beat Sen. John Kerry 78 percent to 21 percent among these voters.
Asked whether McCain has an advantage with evangelicals, Warren said he's not going to predict how the influential religious group will vote. Watch more on the evangelical vote »
He added, "I can tell you this: They're not a monolithic bloc, as the press frequently tries to make them out to be. I think that for many evangelicals, they're not convinced that either of these men is an evangelical. They may be believers in Christ, they may be Christian, but they want to know, for instance, their worldview. And they want to hear it out."
But even as former Arkansas Gov. Mike Huckabee -- who was thought to have locked up the evangelical vote given his background as a Baptist minister -- made a strong showing in the GOP primaries this year, McCain was pulling in a substantial number of evangelical votes.
McCain, who was raised an Episcopalian and now identifies himself as Baptist, rarely discusses his faith.
"I'm unashamed and unembarrassed about my deep faith in God. But I do not obviously try to impose my views on others," McCain said in April.
Since then, the senator from Arizona has met with many of the evangelical leaders who did not support his candidacy during the primary season. At a private meeting this summer, dozens of the movement's most prominent figures voted to support his campaign.
While the two candidates are taking questions from Warren, a daylong assembly of evangelicals will be wrapping up at the other end of the country.
Huckabee and the Family Research Council's Tony Perkins are among speakers and musical acts appearing before what the cross-denominational group TheCall describes as a day of fasting and prayer on the National Mall in Washington.
While organizers said the rally isn't a political event, it will address values issues such as abortion and same-sex marriage.
By some accounts, both campaigns' grass-roots efforts to rally the conservative Christian base have lagged recently.
Meanwhile, Obama's positions in favor of abortion rights and same-sex civil unions also have created tension among evangelical voters otherwise drawn to his candidacy.
But the Democrat, who is Christian, has made it a point to discuss his religion on the trail this year and launched an ambitious outreach effort targeting these voters, including private summits with pastors and a major campaign aimed at young evangelicals.
href="http://www.cnn.com/ELECTION/2008/candidates/barack.obama.html">Obama's evangelical supporters, including members of the new Matthew 25 Network political action committee, rallied around the Democrat in June when Christian conservative James Dobson accused him of "deliberately distorting the traditional understanding of the Bible."