WASHINGTON -- Americans have never seen anything quite like the nine days of presidential and vice presidential debates that start Sunday evening in St. Louis.
It's not just that there will be three candidates on stage for the first time in a general election. Or so many debates jammed into so short a time. Or even that the encounters could be President Bush's last hope of reversing the powerful political tide that threatens to sweep him out of the White House.
What's likely to be special this time, debate experts say, is the content of the debates. Instead of a contest of snappy one-liners and calculated one-upmanship, the 90-minute sessions may focus more on the real issues troubling voters -- the economy, jobs and the deficit.
That's because Mr. Bush, Bill Clinton and Ross Perot have already appeared repeatedly in similar formats -- on the morning news shows and the late-night talk shows, joshing with their hosts and fielding questions phoned in by ordinary citizens.
"This year is unique," says David S. Birdsell, a social scientist at New York's Baruch College and co-author of a book on presidential debates. "Bush has already shared the same stage with his opponents -- albeit at different times. That diminishes presidential stature as an issue. So the debates can focus more directly on the comparison of ideas and pursue the candidates' positions in depth."
There is much at stake for each candidate -- although the risks are unevenly distributed. Mr. Bush has the most to gain or lose, Mr. Clinton less and Mr. Perot the least.
For Mr. Bush, stuck 10 points or more behind Mr. Clinton in polls since Labor Day, the debates are a crucial opportunity to narrow the gap and put him in striking distance for the final -- to Election Day.
The debates are also Mr. Clinton's best chance to help voters overcome doubts about his personal qualities as a prospective leader -- doubts that the Bush campaign is working hard, with some success, to sharpen.
In addition, they offer Mr. Perot an opening to redeem his reputation as a quitter and a spoiler by elevating the tone of the debates and forcing Mr. Bush and Mr. Clinton to address the deficit seriously.
A major problem for Mr. Bush is that he needs to win the debates outright in the public mind. Political professionals say the president cannot settle for a tie.
"When you're running 10-15 points behind in the polls, you have to hit a home run, and if he doesn't, I think he loses," says Sen. Lloyd Bentsen, D-Texas, the 1988 Democratic vice-presidential candidate.
Republican strategists agree that a good showing in the debates is crucial. "It's clearly an opportunity for us to kick out of the stall we've been stuck in and overtake him (Clinton)," says James Lake, a senior Bush campaign adviser.
Unfortunately for Mr. Bush, debates tend to reinforce the attitudes of those who already have decided how to vote.
"Most presidential debates don't markedly alter the electorate's perceptions of the candidates," says Kathleen Hall Jamieson, an authority on political attitudes at the University of Pennsylvania. "When perception does change, that change generally favors the less well-known candidate, Kennedy in 1960, Reagan in 1980."
Even the "winner" lies in the eye of the beholder. Eight out of 10 of Ronald Reagan's fans thought he won his 1980 encounter with Jimmy Carter. Seven out of 10 Carter supporters thought Carter won.
The 1988 debates between Mr. Bush and Michael Dukakis had little effect on the outcome. Only a quarter of the voters said the debates were a major factor in their decision, according to exit polls taken by ABC News.
But Mr. Birdsell says it is hard to imagine a debate scenario this year that would help the president.
"The task for Bush is really large and hard to pull off," Mr. Birdsell says. "He has to convince people that he is sensitive to their needs and capable of taking care of them. He tried to do that for months in less difficult forums. It hasn't worked. I can't see what he can do in the debates to turn that around."
The major risk for Mr. Clinton is that he might make a misstatement or handle a tough question badly, as President Ford did in 1976 or Mr. Dukakis in 1988.
However, Mr. Clinton's debating skills were sharpened during the primaries, when he showed himself to be a cautious, if unexciting contestant. He hit no homers, but made no errors.