One of the biggest misconceptions in past elections is that vice presidential nominations really count. But most of the time, they have had the electoral impact of a bucket of warm spit, to paraphrase Franklin Roosevelt’s sardonic Vice President John Nance Garner.

The Democrats’ relentless attacks on then-little-known Indiana Sen. Dan Quayle in 1988 couldn’t prevent Democrat Michael Dukakis from getting thumped. Dumping Quayle four years later wouldn’t have saved George H.W. Bush.

But at the risk of again falling into the Veep Hype, it could be different in ‘08. Democrats have several strong choices that could fill issue or experience vacuums, or placate wounded demographic groups. Republicans have regional and ideological choices that could help Arizona Sen. John McCain build a bridge to a wary right wing.

If front-runner Barack Obama, D-Ill., wins his party’s nomination, Sen. Hillary Rodham Clinton, D-N.Y., would complete the dream ticket of many Democrats. But could Clinton take another back seat in the White House after spending eight years in a supporting role during her husband’s presidency? For her, being a senator from New York might be more influential no matter which party controls the White House in 2009. And would Obama really want to deal with the super-sized presence of Bill Clinton, who has been at best a mixed blessing for his wife this primary season?

If Sen. Clinton captures the nomination, there would be immense pressure to pick Obama. But would he want it, given that a Clinton nomination would almost certainly have come after a rough takedown of Obama, whom many Democrats perceive as the second act of Camelot? For Clinton, a running mate like Gov. Ted Strickland of Ohio would be an important asset in the ultimate swing state. He would help drive home Clinton’s populist economic message.

For Obama or Clinton, a strong contender would be Bill Richardson, the New Mexico governor and failed ‘08 candidate who has hinted he could soon endorse.

Richardson could help fill Obama’s lack-of-experience vacuum because he has been a governor, Cabinet secretary, a United Nations ambassador and negotiator with some of the world’s worst dictators and most secretive regimes, including North Korea. He is also Hispanic, a demographic that could cast 7 percent to 8 percent of the votes in November. And New Mexico’s last two presidential elections have been decided by a miniscule 365 votes for Al Gore in 2000 and 5,988 for George W. Bush in 2004.

At 50, Arizona Democratic Gov. Janet Napolitano would enhance the generational change argument Obama, 46, will try to press against the 71-year-old McCain. Napolitano does not have Richardson’s foreign policy experience, reinforcing a McCain argument that Democrats were offering inexperience in dangerous times. But Napolitano could help placate disappointed women who saw in Clinton an opportunity to break a glass ceiling into the Oval Office. Kansas Gov. Kathleen Sebelius, 59, might represent the same message.

For McCain, former primary rivals Fred Thompson and Mitt Romney could help with conservatives, but Thompson ran an uninspired campaign and McCain and Romney have a rocky personal relationship. Former Arkansas Gov. Mike Huckabee may be wearing out his welcome while he makes jokes about his refusal to concede. Secretary of State Condoleezza Rice would balance McCain’s gender and race, but she has said she won’t run, and it’s unclear where she stands on issues like abortion rights. Sen. Kay Bailey Hutchison, R-Texas, will be 65 in July, no age balance for McCain.

Securities and Exchange Commission head Chris Cox of California, said to be on George W. Bush’s short list in 2000, could help McCain in the Golden State. Former congressman and Office of Management and Budget Director Rob Portman could help McCain in Portman’s native Ohio, but some think Portman is too close to President Bush.

GOP governors are the key. Mark Sanford of South Carolina, who early last year rebuffed a scouting party of cultural conservatives who implored him to run, would appeal to those who think McCain has been hostile to religious conservatives. Party leaders like Gov. Haley Barbour of Mississippi, but his resume includes time as a lobbyist and Republican National Committee chairman, and that would undermine McCain’s challenge to the status quo. Gov. Charlie Crist of Florida has high home-state approval ratings, but some Republicans think Florida will be easier than normal pickings in November because Floridians are angry that the Democratic National Committee refuses to recognize their delegates and allow them a seat at the national convention in August.

The most logical road leads to Gov. Tim Pawlenty, 47, of Minnesota. He shores up McCain on age and executive experience. Pawlenty was one of McCain’s earliest endorsers. Tactically, Pawlenty could concentrate on the politically and culturally similar swing states of Iowa, Minnesota and Wisconsin, which collectively have 27 electoral votes.