Why isn't Barack Obama doing better against John McCain in the opinion polls? For a big part of the answer, look no further than Saturday night's forum at Saddleback Church.

Both candidates spent an hour, separately, answering the same questions from Pastor Rick Warren. On substance, no one who has been following the race heard anything surprising. But the contrasting styles of McCain and Obama said a lot about the kind of leader each man is and would be.

Obama spoke with customary coolness and intelligence but tended toward vagueness. When the minister asked how our nation should respond to evil, Obama made the perfectly defensible point that while evil should be confronted, we should bear in mind that we could unintentionally do evil despite our good intentions. Yet he offered no concrete examples.

McCain, by contrast, responded forcefully and unambiguously. "Defeat it," he growled, then spoke hotly about terrorism, using specific instances to underscore his point. Given the Iraq debacle, McCain ought to take Obama's insight more seriously. You can be clear — and clearly wrong. Nevertheless, you know where McCain stands.

Obama, though, has struggled to define himself in the public eye. Some top Democrats have urged him to be less ruminative and more plainspoken. As Gov. Phil Bredesen, the Tennessee Democrat, told the New York Times last weekend, "Instead of giving big speeches at big stadiums, he needs to give straight-up 10-word answers to people at Wal-Mart about how he would improve their lives."

Good advice. Presidents are not professors. Elections aren't decided by cold rationality, but largely by character judgments. Intellectual capability doesn't much matter if you cannot articulate persuasively what you believe and why you believe it, and win the confidence of the American people. Ask Presidents Dukakis, Kerry and Gore.