LEXINGTON, Ky. -- Near the end of the first debate ever of vice-presidential candidates, Senator Bob Dole remembered his White House-prepared briefing materials on war casualties under various administrations -- and used them.
"If we added up the killed and wounded in the Democrat wars in this century, it would be about 1.6 million Americans, enough to fill the city of Detroit," Mr. Dole, a Kansas Republican, said on Oct. 15, 1976.
Walter F. Mondale, his Democratic rival, was ready. His briefers had anticipated the attack. "Senator Dole has richly earned his reputation as a hatchet man tonight," said Mr. Mondale, who instantly concluded that the exchange had made him the debate's winner.
By now, Mr. Dole suspects that, too. The debate "should have been canceled," said Mr. Dole, as sardonic as ever at age 89.
Given the tinted lenses through which partisans view debates, some Republicans nevertheless thought he had held his own.
"I thought Dole did great," recalled Dan Quayle, who was running for a Congressional seat from Indiana that year. Mr. Quayle won, even as President Gerald R. Ford and Mr. Dole lost to Jimmy Carter and Mr. Mondale.
Mr. Quayle is living testimony to how vice-presidential debates can leave lasting impressions. In. 1988, as the Republican Party's 41-year-old vice-presidential nominee, he defended his qualifications by noting, "I have as much experience in the Congress as Jack Kennedy did when he sought the presidency." That line set up the most famous smackdown in debate history.
"I served with Jack Kennedy," his 67-year-old Democratic opponent, Lloyd Bentsen, responded coolly. "Jack Kennedy was a friend of mine.
"Senator, you're no Jack Kennedy."
Jubilant Democrats erupted inside the Omaha Civic Auditorium.
As difficult as the moment was for Mr. Quayle -- "uncalled-for," he glumly told Mr. Bentsen -- he was elected vice president the next month when his running mate, George Bush, trounced the Democratic nominee, Gov. Michael S. Dukakis of Massachusetts.
"It was a good line for him," Mr. Quayle recalls now. "Did it move the needle? No."
Vice-presidential debates rarely do have a significant impact on the outcome of elections. At best, observed Tad Devine, a Democratic strategist, they can increase momentum for a ticket considered to have won the first debate of the presidential nominees, or serve as "a circuit breaker" for the ticket that lost.
That is precisely what President Obama hopes his experienced vice president, Joseph R. Biden Jr., can do in his debate in Danville, Ky., on Thursday against Mitt Romney's youthful running mate, Representative Paul D. Ryan.
Eight years ago, Vice President Dick Cheney showed how it is done.
Mr. Cheney -- the chief of staff in the Ford White House that gave Mr. Dole those ill-fated 1976 briefing materials -- faced off in Ohio against a first-term senator, John Edwards. His boss, President George W. Bush, had been throttled a few days before in his first debate with the Democratic nominee, Senator John Kerry.
Projecting calm and gravitas, Mr. Cheney rebutted the Democrats' attacks while casting Mr. Edwards as a lightweight. Citing Senate votes the young North Carolinian had missed, the vice president observed cuttingly, "The first time I ever met you was when you walked on stage tonight."
Mr. Devine, then a top Kerry adviser, said, "He sort of stopped the bleeding for Bush." He does not remember the event as fondly as the vice-presidential debate in 1988, when he served as Mr. Bentsen's campaign manager.
More commonly, voters (and comedy writers) recall vice-presidential debates for clever or amusing flourishes that proved less consequential.
"Who am I? Why am I here?" mused the retired Adm. James B. Stockdale, who was the independent candidate H. Ross Perot's running mate in 1992. Mr. Perot's own solid debate performances that year helped him garner 19 percent of the vote as Gov. Bill Clinton of Arkansas defeated the first President Bush.
In the next election, Jim Lehrer, the moderator, invited the Republican vice-presidential candidate, Jack Kemp, to open the debate by discussing President Clinton's ethics. "Wow, in 90 seconds? I can't even clear my throat in 90 seconds," Mr. Kemp replied, adding, "Jim, Bob Dole and myself do not see Al Gore and Bill Clinton as our enemy."
That was not exactly the tone that Mr. Dole, having led the attack for President Ford two decades earlier, wanted from his running mate. "He could have been a little tougher," said Mr. Dole, whom Mr. Clinton defeated handily four weeks later.
In 2000, Joseph I. Lieberman, the Democratic vice-presidential candidate, led off his debate with Mr. Cheney by vowing, "I'm going to be positive tonight." His performance failed to stem the progress that Gov. George W. Bush of Texas had begun in his first debate with Vice President Al Gore.
Even the most electric vice-presidential candidate of recent years, Gov. Sarah Palin of Alaska, did not deliver any line more memorable than when she greeted Mr. Biden at the 2008 debate with "Hey, can I call you Joe?"
Vice-presidential candidates, Mr. Quayle argued, need to ignore their debating partners and relentlessly go after the top of the opposing party's ticket. Despite Mr. Bentsen's brutal riposte, he said, he helped Mr. Bush assail Mr. Dukakis in 1988 and Mr. Clinton in 1992. He has discussed the role with Mr. Ryan, but insisted that Republicans should not underestimate the challenge Mr. Biden could pose.
"He's basically smart," Mr. Quayle said of his onetime Senate colleague. "Where he makes his mistakes is when he goes out and freelances. He won't be freelancing on Thursday night."
Mr. Dole cautioned against concluding that the event will not matter, whoever performs better.
"Ryan is going to be hard to beat on facts and figures," he said, but "I imagine Joe's going to come out fighting, and he's not going to let up."
In such a close race, Mr. Dole concluded: "It might make a difference. Not much, but enough to measure."
This article originally appeared in The New York Times.