New York University's Paul Light is one of the few scholars out there considered an expert in the vice presidency.
"Frankly, you can take over an entire field like this with one book," said Light, whose "Vice Presidential Power" hit the presses in 1983.
Light, a former Minnesotan, has been trying to leave the subject behind ever since. But every four years, the reporters come calling.
Last time around he joked to The New Yorker magazine that he'd offer a $10,000 reward to anyone who wanted to take his place as America's vice presidential pundit.
"People actually sent me letters asking for the money," he said, but much to their chagrin, Light decided to keep the job and the money.
One reason he'd gotten sick of talking about running mates is a lot of them don't do very much.
In 1969, Hubert Humphrey, the Minnesota Senator who served as Lyndon Johnson's vice president, told TIME magazine the job was "like being naked in the middle of a blizzard with no one to even offer you a match to keep you warm."
Constitutionally, the veep's only official duties are to break the occasional tie in the Senate and, of course, step in if the president dies, resigns or is removed from office.
And so it was, for the first 200 years of American history. That is, until Jimmy Carter came along.
"I am determined, beyond what has ever been done in this country, to put major responsibilities on the vice president, if I'm elected president," Carter said as he announced his running mate back in 1976. It was another Minnesota senator named Walter Mondale.
"I was the first vice president to actually be part of the executive branch and to work daily with the president, in an office forty feet away from his," Mondale told Minnesota Public Radio in an interview two years ago.
Since then, vice presidents have tended to follow the Mondale model, with Dick Cheney taking the power of the office to a whole new level.
So, what about the current presidential contenders? What might they be looking for in a potential running mate?
"It used to be that you looked for geographic balance," said Light, the reluctant vice presidential scholar.
So if you were from the north, you might want to run with someone from the south. More recent candidates have broken from that, though.
Bill Clinton chose Al Gore, even though they were both from the south. George Bush asked Cheney to help him find the perfect running mate.
"And gradually," the president said as he announced his choice in Austin Texas, "I realized that the person who was best qualified to be my vice presidential nominee, was working by my side."
Cheney found himself, even though, just like Bush, he hailed from the west.
"The geographic test has kind of faded away," Light said, "but it's now back with a vengeance, because the candidates know that they've got to win a couple of battleground states."
Battleground states are places like Florida, Ohio and Pennsylvania. They could swing either to the Democrats or the Republicans, and consequently swing the election. Light says odds are the candidates are looking for running mates from those states.
In Light's analysis that means John McCain probably won't ask Tim Pawlenty to join the ticket.
"What can he deliver that McCain needs is the question," Light said. "At this particular point, I don't think Pawlenty can add very much except gubernatorial experience and youthfulness."
Light doesn't think Minnesota has much chance of swinging Republican this year. Gov. Charlie Crist, R-Fla., seems like a better bet to him. Crist is a McCain backer, too, and he's been coy when asked if he wants to be vice president. Pawlenty has all but vowed to turn down the job, even if McCain offered it to him.
"I said I would serve out my term as governor, if I was re-elected, and that's what I intend to do," Pawlenty told Minnesota Public Radio after winning his second term.
Paul Light is also skeptical about the other big topic of running mate speculation -- a Clinton/Obama or Obama/Clinton ticket.
"I think it's got a zero-probability at this particular point," he said.
Again, Light says both Democrats would be better off with a governor from Pennsylvania or Ohio.
But even then, Light says it's important to keep all this running mate stuff in perspective: "The vice president from an electoral standpoint might be able to deliver a state, maybe, and might account for 1-2 percent of the popular vote."
And chances are, it'll be months before any candidate will announce a running mate. In fact, it's likely to be within about a week of the parties' national conventions in late August/early September. That is, if recent history is any guide.