Washington - Lowering expectations before a political debate is an old trick to make the outcome seem more positive.

Ahead of Thursday's debate between the vice-presidential candidates, expectations are indeed very low.

Following the initial enthusiasm after they were picked a month back, Democrat Joe Biden and Republican Sarah Palin have seemed to compete for who can commit the worst mistakes - Palin for her poor oratory or Biden for his excessive oratory.

Be it for the joy of seeing a public figure fail miserably or for the chance that their performance might in fact improve, the truth is that the vice-presidential debate is highly-anticipated.

Some 3,100 journalists have been accredited to cover the debate at Washington University in Saint Louis, Missouri, and the event is set to be broadcast by all major US television networks.

Palin stands to win the most, and not just because her two years as governor of Alaska - the third-least populous state in the country - will be facing the 36 years that Biden has sat in the Senate.

Despite being protected from the media by the campaign of Republican presidential candidate John McCain, Palin's gaffes in three recent interviews have provided much fodder for late-night comedians.

Her comments citing Alaska's proximity to Russia as foreign policy experience or mixing the 700-billion-dollar proposed rescue plan for the US economy with job creation, healthcare reform and tax reductions have led some conservative commentators - who are supposed to be on her side - to publicly ask that Palin bow out of the race for the good of McCain and the country.

"It's going to be very, very hard to erase the impression she's given in the network TV interviews that she is in way, way over her head and she's not ready for prime time," said commentator Rod Dreher.

If anyone looks like they can save Palin, it is Joe Biden, chosen by Democratic presidential candidate Barack Obama for his international expertise.

The senator from Delaware is a great orator with an extensive vocabulary and a talent for improvisation. He is almost equally skilled at taking his rhetoric too far.

Last week Biden said the current economic crisis needed a leader like US president Franklin Delano Roosevelt, who calmed down the country after the stock market crash of 1929 with just a television appearance.

It would have been a great story, but for the fact that Herbert Hoover was president on that Black Tuesday and no US citizen had a television set at the time.

Biden is older and has a longer record of mistakes. The most famous dates back to 1987, when his first presidential candidacy collapsed after it was discovered that he had plagiarized parts of a speech by a British politician.

The veteran senator has an additional problem. Facing a woman with a lot less experience than himself, Biden will have to avoid adopting "a posture of being aggressive toward her or, worse, condescending," said Bob Shrum, who helped John Kerry prepare his presidential debates in 2004, in an interview to Newsweek.

Palin should exploit her more personal side, put herself forward as "a likable, caring person who believes what she says," said Stuart Stevens, who helped Republican Vice President Dick Cheney prepare for debates with Democrats Joe Lieberman and John Edwards in 2000 and 2004 respectively.

Stevens may well have left his best advice for last: "Her goal should be to not make news." (dpa)