The event was Palin's debut in a debate of candidates for national office — in contrast, Biden participated in 14 before he dropped out of the presidential race on Jan. 3 — and was watched by many millions of Americans eager to see how the self-described "hockey mom" with scant national experience would fare against Biden, the chairman of the Senate Foreign Relations Committee and a voluble, gaffe-prone 35-year veteran of Washington.

The event was held in the Field House of the athletic complex at Washington University in St. Louis, the host of presidential debates in 1992, 2000 and 2004 and site of a bellwether state that has voted for the winner in every presidential election of the last 48 years.

Biden wore a flag pin on his lapel, just as his running mate did at the presidential debate last week. Palin wore a larger — and shinier — American flag on her suit, leaving McCain as the only one of the four candidates who did not have a flag affixed to his suit.

Both of the vice presidential candidates frequently wore wide smiles — often at the same time — that were shown on television screens in side-by-side shots. Palin repeatedly looked directly at Biden — something her running mate did not do as he addressed Sen. Barack Obama — and he returned the glance even as he pointed out distinctions.

The scene on the stage Thursday evening offered to voters, in effect, a mirror image of the presidential debate last week. As a contrast to last week, this time the Republican candidate presented herself as a fresh agent of change, while the Democratic candidate often drew upon his long Washington experience as he answered his questions.

Palin returned again and again to energy policy, which she clearly feels is her strongest suit, and faulted "East Coast politicians" for failing to allow more oil drilling in Alaska. She did not mention her differences with McCain on drilling in the Arctic National Wildlife Reserve, which she supports but her running mate opposes.

"Barack Obama and Sen. Biden, you've said no to everything in trying to find a domestic solution to the energy crisis that we're in," Palin said. "You even called drilling — safe, environmentally friendly drilling offshore — as raping the outer continental shelf. There — with new technology, with tiny footprints even on land, it is safe to drill, and we need to do more of that."

When Palin, who has expressed doubts in the past that global warming is caused by man, was asked what she thinks about climate change, she continued to express doubts.

"I'm not one to attribute every activity of man to the changes in the climate," she said. "There is something to be said, also, for man's activities, but also for the cyclical temperature changes on our planet. But there are real changes going on in our climate, and I don't want to argue about the causes."

Biden was more direct about what he thinks the causes are. "I think it is man-made," he said. "I think it's clearly man made."