ON JULY 27, Barack Obama, the Democratic candidate for the U.S. Senate in Illinois, will deliver the keynote address at the Democratic National Convention in Boston. The keynote address is a coveted opportunity, a chance for silver-haired politicos to deliver their swan song to an adoring crowd, or for bright new talent to make its debut. Obama falls into the bright new talent category. If he is elected this November, he will become only the third black U.S. senator since Reconstruction ended in 1876. Millions of people will watch him on July 27. A young man named Justin Warfel won't be one of them.

"Maybe I'll read about it in the paper," Warfel said by phone the other day, as he walked outside his home in Springfield, Illinois. For a while he was seeing a lot of the 42-year-old Obama. Perhaps too much. For about two weeks in May, Warfel, his Panasonic digital video recorder in hand, followed Obama everywhere the candidate went, to campaign events in downstate Illinois, to speeches at the capitol in Springfield, to press gaggles outside campaign headquarters--day after day, sunrise to sunset.

Warfel was no stalker. He was a tracker: a campaign operative who engages in hands-on opposition research by recording all that an opponent says or does. Tracking is nothing new. Before video cameras, trackers--often young, ambitious party flacks--would follow candidates with tape recorders. Before that, the tools of choice were pad and pencil. "It's something countless other campaigns have done before," Warfel said. "Obama had his people tracking Jack as well."

"Jack" is Jack Ryan, who until recently was Obama's Republican opponent, as well as Warfel's employer. In June, however, Ryan pulled out of the race. A court had released embarrassing testimony from a child custody battle with his ex-wife, the actress Jeri Ryan. Warfel, who now spends his days "relaxing," thinks Ryan was betrayed by the Illinois Republican party in general and chairwoman Judy Baar Topinka in particular. "Jack's campaign was a good campaign," Warfel said. "You had a superlative candidate. You had a guy with firm beliefs. And if you'd had a situation where the Illinois Republican party rallied around their candidate, the court stuff would have been a two-day story, and Jack would have gone on to win in the end."

And yet, by the time he dropped out, Ryan was clearly losing the race to Obama. One poll showed him as much as 20 points behind. A combination of factors plagued the Ryan campaign: Illinois has been trending Democratic, for one. Ryan, a former investment banker, had no government experience, for another.

Then there is Obama himself. He is a brilliant man and an impressive orator. Also, he has an unusual life story--unusual enough that he published a memoir, Dreams from My Father, before becoming an Illinois state senator. Obama was born in 1961 in Hawaii, where his father, a student from Kenya, was studying economics. His mother was 18.

When Obama was 2, his father left the family to return to Kenya, where he eventually became finance minister. Abandoned, Obama's mother, an anthropologist, married a man who worked in the oil business. The family moved to Indonesia, where they spent four years. Then Obama returned alone to Hawaii, where he was raised by his grandparents and attended Punahou, a tony prep school. The Ivy League followed: first Columbia, and then, after four years working as a community activist in Chicago, Harvard Law. In 1990, he was elected the first black president of the Harvard Law Review and saw his first round of adulatory press. It was already clear that Obama wanted to enter politics. He told reporters he would return to Chicago eventually. Chicago, he said, was "an ideal laboratory." He won his state senate seat in 1996.

I asked Justin Warfel whether Obama's biography explains his appeal.

He scoffed. "Obama himself doesn't really interest me," he said. His voice was intense. "What's scary, though, is that he's able to portray himself in a moderate light. He's got so many people into thinking he is not the far-left candidate he is. But when you look at the issues, on abortion, on the gun issue, well, it's scary."