The Times previews Barack Obama's keynote address to the Democratic Convention tomorrow night: It came as a surprise that I'd be selected for such a privileged position," Mr. Obama said on a recent afternoon, as he sat in his Springfield office and reflected on what he may tell a national audience in Boston on Tuesday night. "As my wife reminds me, I better not screw it up." Even before he breathes a word to the widest audience of his career, just the prospect of the speech has propelled Mr. Obama into the spotlight. He spent Sunday morning answering questions on network news programs along with better-known figures, the leaders of the Sept. 11 commission and the governors of Michigan and New Mexico. Mr. Obama, a state senator who represents Chicago's South Side, said he intended to describe what he has heard as he has wandered in the Midwest: the economic squeeze people face with jobs that pay less than before and the anxieties they feel about Iraq, but also his sense of Americans' resilience and strength. "Ultimately," he said, "it is a hopeful story I want to tell." One point listeners are unlikely to hear is his opposition in 2002 to Congress's approval of the war in Iraq. Senators John Kerry and John Edwards voted to authorize it. Last week, Mr. Obama was waiting for editing of his draft from Mr. Kerry's campaign, but said he hopes to deliver mostly his own words, written, thankfully, he said, before he realized what a big deal the keynote was, before he had a chance to develop writer's block. Stephanie Cutter, communications director for the Kerry campaign, explained why the campaign chose Mr. Obama, a former community organizer and Harvard-educated civil rights lawyer: "We believe he represents the future of the party." Mr. Kerry's supporters say they hope the choice will also sway those who have accused Mr. Kerry of failing to include enough minorities in top campaign roles and, more broadly, of failing to excite black voters. "This represents the Democrats reaching out," the Rev. Jesse Jackson said. "It's important because the destiny of the Democratic Party is tied up, in some sense, in the growth of the minority base." Just remember: Little Wild Bouquet was into Barack Obama before he was a star.