The dark art of the vice presidential debate begins with a single rule: If everybody's talking about you, you're doing it wrong.
Since 1976, there have been eight televised face-offs between vice presidential nominees. The ninth will come Thursday, when Vice President Biden debates Republican Rep. Paul Ryan (Wis.) in Danville, Ky.
By now, both parties have worked out tactics to fit this odd ritual. They require the barbed wit of an insult comedian and the humility of the hind legs in a two-man horse costume.
Candidates are told: Talk up your running mate. Zing your opponent. But avoid letting your career or your policy ideas become the focus. On the biggest night of your political life, it's not about you.
On Thursday, the stakes will be unusually high, and the job of playing second banana especially tough. Biden spent 36 years in the Senate. Ryan crafted a plan for remaking the entire government.
Now, the proud, successful men will have to insist — convincingly — that they'd rather talk about somebody else.
"Whatever you stood for, you stand for the team now," said Samuel Popkin, a professor at the University of California at San Diego who has helped coach Democrats in debates. Popkin said the task might be especially touchy for Ryan, because Romney has said he would not adopt Ryan's famous budget plan in full.
"You need his goal in life to be power now, not power later," Popkin said. "The only way I can see you do that is to get Ryan to say, 'Romney's budget is better than what I started with.' "
By tradition, the vice presidential debates have been like the vice presidency itself: well- publicized but largely inconsequential.
At the polling firm Gallup, researchers recently analyzed survey results before and after every running-mate debate since 1976 (except 1980, when there was no debate). "We really don't see any statistical change in any of them," said Frank Newport, Gallup's editor in chief.
But this year, both parties hope, could mean much more.
Democrats hope that Biden can make up for Obama's tentative, defensive performance in the first presidential debate last week. That would mean attacking Ryan over Romney's plans for taxes, Medicare and the budget, and pointing out where Romney's ideas conflict with Ryan's.
Republicans, by contrast, think the numbers-focused Ryan will extend his party's win streak to two. Ryan began his debate preparations a month ago, holding three mock debates, with former U.S. solicitor general Ted Olson playing Biden. He then spent three days last week huddled in "debate camp" in southwest Virginia.
Neither of these men, however, has ever faced a challenger like the other.
Biden played two roles in the previous presidential campaign cycle: In the Democratic debates, he was the loose, bomb-throwing long shot. During the general-election season, he faced not a wonk but a political neophyte, then-Alaska Gov. Sarah Palin (R), in the vice presidential debate. Biden's job was to be polite; repeat talking points about Palin's running mate, Sen. John McCain (Ariz.); and stay out of the way. He did.
Ryan, the House Budget Committee chairman, has sparred with Democrats before on issues of taxes and spending. He often uses a genial, prodding demeanor, which suggests that he is saddened by his opponents' missteps but hopeful that his challengers can reform.
But a TV interview this week suggested that Ryan may have little practice handling what he is likely to get from Biden: criticism on issues beyond the budget. A local reporter in Michigan asked Ryan whether the country had a gun problem. Ryan's answer wandered, but it wound up with the argument that economic development, not gun control, is the cure for urban violence.
"You can do all that by cutting taxes, with a big tax cut?" the reporter asked.
"Those are your words, not mine," Ryan said. Then a press aide cut off the interview.
On Thursday, Biden and Ryan will participate in a ritual that, despite looking like a standard presidential debate, has its own peculiar set of traditions.
A big one: Vice presidential debates are rarely "won" in any meaningful way. A smart, polished performance by any running mate is usually forgotten after the next presidential debate.
But a vice presidential debate can certainly be lost — in a way that haunts the campaign or the even the career of the running mate who lost it.
"I recall pretty distinctly saying, 'You can't compare . . . yourself to Kennedy,' " said Kenneth Khachigian, a longtime Republican debate adviser, remembering his advice to then-candidate Dan Quayle in the run-up to the 1988 debate. Quayle liked the analogy: He and former president John F. Kennedy had similar experience in Congress.
But Khachigian said no: "You're comparing yourself to a memory."
Quayle did it anyway. Across the aisle, Democrat Lloyd Bentsen had been waiting.
"I served with Jack Kennedy. I knew Jack Kennedy. Jack Kennedy was a friend of mine," he said, looking like it pained him to point this out. "Senator, you're no Jack Kennedy."
In fact, the highlights of vice presidential debates have usually been lowlights, when a running mate stumbles so badly that it makes the top of the ticket look bad. Sometimes, those errors are unforced: In 1992, Ross Perot's vice presidential pick might have provided the best evidence that Perot's campaign was not ready for the big time.
"Who am I?" said retired Adm. James Stockdale. "Why am I here?' "
In other instances, the job was done a single well-timed put-down.
"I'm up in the Senate most Tuesdays when they're in session," Vice President Richard B. Cheney told then-Sen. John Edwards (D-N.C.) in 2004. "The first time I ever met you was when you walked on the stage tonight." That turned out not to be true. But for Edwards, it still hurt.
In 1976, the most memorable line of the first vice presidential debate was probably an insult from Democrat Walter Mondale. Republican Bob Dole had been hard-edged in his criticisms, at one point lumping Vietnam, Korea, World War II and World War I together as "Democrat wars."
"Senator Dole has richly earned his reputation as a hatchet man," Mondale said. Even in the moment, he knew he had done something: "I think that stuck a little bit. Because he was off his game, no question about it," Mondale said in an interview this month. Afterward, "he did seem sort of insecure to me."
For Biden and Ryan, debate experts say, the way to avoid this kind of personal zinger is not to talk about yourself in the first place. And, if the other candidate makes you the issue, return the favor.
It will make him as uncomfortable as you.
"What's good for goose number one is good for goose number two," Khachigian said. He suggested that if Biden criticizes Ryan over his budget, Ryan should respond by dredging up Biden's past positions as a senator. "I'd be lying in wait for that to happen, and I'd have Biden's 10 most outrageous positions."