The public clash tomorrow between would-be vice presidents, ill-informed newcomer Sarah Palin and gaffe-prone veteran Joe Biden, is attracting unusual attention.
Already 3,100 media credentials have been issued for the debate, the most the Commission on Presidential Debates ever needed in the seven vice presidential debates it has hosted.
The interest is driven by the public's fascination with Mrs Palin, the first-term Alaska governor that Republican presidential candidate John McCain plucked from relative political obscurity to be his running mate.
Initially, Mrs Palin was praised as a superb political communicator for the delivery of her acceptance speech at the Republican National Convention four weeks ago.
She energised the party's conservative base, which had reservations about Mr McCain.
But a series of shaky Palin television interviews have left even some conservatives questioning whether she is ready to be vice president.
She could not describe the Bush doctrine in foreign affairs, seemed to have little grasp of the proposed financial industry bailout and even appeared to endorse Democratic presidential candidate Barack Obama's position on chasing al-Qaida terrorists in Pakistan.
Mrs Palin's performance against Mr Biden, the Delaware Democrat with 35 years in the Senate, could restore her initial appeal or seriously weaken the Republican ticket.
Last week's Obama-McCain debate appeared to give Mr Obama, a US senator from Illinois, a small boost in the polls but produced no knock-out blows, so the vice-presidential debate at Washington University in St Louis could be a pivotal moment in a race already filled with surprising twists.
Mrs Palin left the campaign trail on Monday to prepare at Mr McCain's ranch in Sedona, Arizona.
She is being coached by his top campaign strategist, Steve Schmidt, as well as advisers Tucker Eskew, Nicolle Wallace and Mark Wallace, all veterans of President George Bush's political operation.
McCain strategists are well aware that Mrs Palin's glowing image has been badly bruised since the convention.
She has been kept from nearly all contact with reporters except for a handful of high-profile network TV interviews that revealed her relatively thin grasp of foreign policy and domestic issues.
Mrs Palin's answers have become punchlines for comedians, and a mocking impersonation by Tina Fey on the comedy show 'Saturday Night Live' has become a television and YouTube sensation.
As a result, Mrs Palin is under heavy pressure to show a passing command of issues facing the next president.
"I don't think she can get away with comments on foreign policy like she knows about Russia because it's near Alaska," Minnesota-based Republican strategist Tom Homer said.
Mrs Palin needs to "show ability to think on her feet and to engage with someone on the level of Senator Biden without a teleprompter in front of her," he added.
In the CBS interview, Mrs Palin also said she:
- Would not "solely blame all of man's activities" for climate change, noting that world weather patterns are cyclical and have changed over time.
"But it kind of doesn’t matter at this point, as we debate what caused it," she said. "The point is: It's real. We need to do something about it."
- Supports safe and legal contraception, except the morning-after pill because of her belief that life begins at conception.
"I am all for contraception. And I am all for preventative measures that are legal and safe, and should be taken but ..., again, I am one to believe that life starts at the moment of conception."
Pressed on the point, Mrs Palin said: "Personally, I would not choose to participate in that kind of contraception."