ST LOUIS - They were in the same room Thursday night, but Joseph Biden and Sarah Palin often seemed to be participating in separate debates.

One debate dealt with issues. The other served as a platform for Palin's unique brand of Alaskan-bred populism and twangy asides. On the campus of Washington University in St. Louis, the two vice presidential candidates showed off their wildly different styles born of disparate histories. The result was at times an oddly disjointed affair, where the two skittered and shifted off-topic.

With the GOP ticket trailing in national polls, Palin spent most of the time on the attack. She was armed with talking points involving tax increases, domestic drilling for oil, critiques of Democrat Barack Obama's record on the war in Iraq and stinging one-liners. And she repeatedly attempted to steer the debate to allow her to use that ammunition, regardless of the question at hand.

As a result, Biden, the longtime Washington insider, frequently was forced to explain the intricacies of congressional procedure and nuances of international diplomacy, often in a defensive posture.

For Biden, the debate served as much as an introduction to American voters as a test of his mettle. Although the Delaware senator has served in Congress for more than 35 years, he isn't well known nationally. His two attempts to run for president, 20 years apart, were unsuccessful.

His assignment Thursday was simply to maintain the momentum the Obama campaign has been building during the last three weeks. But along with that came a challenge posed by Palin's gender.

He needed to walk a line between respectful and combative -- and avoid coming off as patronizing or condescending. The McCain campaign has made a habit of calling attacks on Palin sexist or elitist.

Palin was not burdened by such concerns and, as befitting her overnight rise from a state politician to a national star, she spent much of the affair showcasing her feisty, salt-of-the-earth personality, employing such phrases as "darn right" and "bless their hearts" and smiling and even winking at the audience. She referred to herself again as a "hockey mom" and said she was talking to "Joe Six-pack."

She said she appreciated the chance to talk to the country without "the filter" of the "mainstream media."

But her folksiness masked a willingness to use a broad brush to attack Obama and Biden, repeatedly suggesting that Obama didn't support the military, saying he sought to make the United States beholden to foreign oil and pushed to increase taxes at every opportunity. Several times, Biden seemed frustrated.

"Facts matter," he said at one point.

She succeeded Thursday in one crucial respect: reestablishing herself as a charismatic, composed performer. The evening had offered a needed opportunity to reverse a growing perception among voters that she lacks the intellectual firepower and experience to be a heartbeat way from the presidency.

Palin's command of the issues had come under heavy fire in the last two weeks, largely because of her interviews with CBS' Katie Couric. Those interviews showed a rambling, sometimes incoherent side of Palin that had not surfaced in pitch-perfect stump speeches crafted by the McCain campaign.

But after Thursday, that question may recede a bit as an election issue, switching again to whether McCain and Palin can present a convincing case that their administration would offer something different than the current one.

And that's where Biden seemed the most commanding. Avoiding directly attacking Palin, he went after McCain again and again: on the economy, branding the Arizona senator as a deregulator who encouraged the current Wall Street crisis; on foreign policy by tying McCain to the war in Iraq; and on health care, where Biden labeled McCain's health care plan, which involves tax credits, "the ultimate Bridge to Nowhere."