WASHINGTON — Sarah Palin brought something more effective than facts and figures to an agriculture debate in the Alaska governor's race. She packed an engaging disposition.

One of her opponents, Andrew Halcro, had memorized the complexities of the subject beforehand. He was super prepared. He might as well have stared out the window during the proceedings, for all it mattered.

"She did such a great job with just the glittering generalities and filling the room with her presence that people didn't care what she said about agriculture," Halcro says now. "Palin's a master at spending 45 seconds telling you what color the sky is," he adds, "and people will say, 'That's the greatest thing I ever heard."'

Palin and her Democratic vice presidential rival, Joe Biden, each bring distinctive qualities and vulnerabilities to the campaign's only running-mate debate, Thursday in St. Louis. It's a potential gold mine and minefield for both.

Biden is a loquacious man of charm and detail with an agile yet unpredictable mind. He can bring the house down with a quip. Two decades ago, he brought his first presidential campaign down with a colossal faux pas in a debate at the Iowa State Fair.

The Delaware senator's debating experience stretches back to 1972 when, as Palin has noted, she was in second grade.

The first-term Alaska governor, however, is no newcomer to political debating, even if she's new to the national big leagues. In 2006, she powered through some two dozen debates, first against an incumbent governor from her own party, then against a former governor from the other side, plus other rivals.

Then as now, she was disparaged as something of a Podunk lightweight — one of the "so-called opponents," in the dismissive words of Frank Murkowski, the GOP governor she would unseat.

Then, she held her own or better in the crush of debates, upending Alaska's political establishment in the process with a one-two punch in the primaries and fall election.

She had a way of disarming opponents that made up for her lack of experience. Biden knows something about that, too.

In his first Senate debate, when he was just 29, he tried an unusual tactic: grace over gotcha.

After his Republican opponent flubbed a question, Biden pretended he didn't know the answer either, so as to avoid rudely upstaging him.

"I probably had better political instincts then than I have now," Biden writes in his recent memoirs.

"Today I'd probably win the point but lose the match because I'd be too busy ripping someone's head off with the facts."

Gulp.

A look at debate highlights and low moments for the running mates of Democrat Barack Obama and Republican John McCain:

THE PALIN EFFECT, 2006

Palin hit some potholes in the blur of debates. Asked to name a good bill and a bad bill that the Alaska Legislature had passed that year, the small-town mayor drew a blank. In one debate, she proposed teaching creationism alongside evolution in schools: "Teach both." The next day, she backtracked.

Asked what she would do about rising dropout rates, she blandly offered: "We need to get kids excited about being in schools." Rivals rattled off specific programs they'd expand.

She skipped several debates entirely.

Even so, the former state oil-industry regulator knew the resource-ownership issues of the day and the arcana of the pipeline project that was central to the campaign. She was a quick study on other matters and generally fast on her feet when she was the lone voice on one side of an issue.

The last debate of the campaign, Nov. 2, 2006, circulates online and has caused some consternation among Democratic-leaning bloggers who warn that Biden may not find her to be a pushover.

Her debate opponents that day were former Democratic Gov. Tony Knowles and Halcro, a liberal independent who was previously a Republican legislator.

Palin fields questions about her conservative views on gay rights, stem cell research and abortion, and pointedly challenges the panelist who asks her a theoretical question that has since become real: What would you do if your daughter got pregnant?

"Again," Palin says evenly, "I would choose life, and certainly I'm quite confident that you're going to be asking my opponents those same scenarios."

Specifics flowed from her opponents on one issue after another. At the end, Palin didn't miss a beat when she was asked whether she'd give her rivals a job in her administration.

For Knowles: "Do they need a chef down there in Juneau? I know that that is what he enjoys doing."

For the studious Halcro: "Andrew Halcro would be the most awesome statistician that the state could even look for," she said with enthusiasm. "Yeah, Andrew would be the statistician."

Halcro runs the family car rental business in Anchorage, now writes a popular blog critical of the Palin administration and has a radio talk show.

BIDEN: POLISH AND PREDICAMENT

The way Biden recalls it, he rushed to the Aug. 23, 1987, Democratic primary debate in Iowa without time to prepare a closing statement. He meant to do so at the scene but rival Jesse Jackson approached him and took up precious minutes tipping him off to the question he was going to ask when each candidate got the chance to grill another.

Biden improvised at the close, reaching mentally into his stump speech and telling a story he had told before, about a coal mining family held back for generations by lack of opportunity.

Only this time, he neglected to credit the source — British Labor Party leader Neil Kinnock.

Biden made it his own story, about his own family, using Kinnock's words and even his inflections.

And to make matters worse, he spoke as if it had all just popped into his head.

"I started thinking, as I came over here," he began, "why is it that Joe Biden is the first in his family ever to go to university. ..."

The consequences were devastating, once the similarities were exposed and a few other tallish tales he'd told were added to the mix. Biden soon pulled out of the campaign.

It's safe to say he is going to his veep debate with a closing statement.

Overall, the 36-year Senate veteran is a polished debater who has learned a lot since his 1972 debut against Republican incumbent Sen. Cale Boggs.

Even in those days, though, he figured he might know too much for his own good.

When Boggs was asked about a genocide treaty important to the Jewish audience at the debate, he answered that he wasn't familiar with it and would have to check on the details.

"I knew the treaty, and I knew the answer cold," Biden says now.

"But I knew enough in 1972 to know that nobody in the audience wanted to see Boggs embarrassed — it would have been like clubbing the family's favorite uncle. So I said, 'I'm not sure. I promise I'll get back to you as well."'

Biden proved to be a live wire in the primary debates of this season, though that didn't get him far — he dropped his second presidential bid after the opening contest in Iowa.

For months, the foreign policy maven had pressed his case on Iraq policy with zest and specifics, and proved adept at hurling zingers at Republicans. His putdown of former New York Mayor Rudy Giuliani's speeches — "a noun, a verb and 9/11" — was one of the keepers of the campaign.

He also leavened debates by poking some fun at himself. When the longwinded senator was asked if he had the discipline needed on the world stage, he shot back with a timely display of brevity, the one-word answer, "Yes."