Continuing our three-part, one-day series, we offer four serious candidates Hillary Clinton might consider for vice president, along with one long shot and one candidate who has no chance of joining Clinton on a ticket. Joining the junior senator from New York, you might see:

Evan Bayh: If Hillary Clinton gets the nomination, the electoral map will probably look as it has for the last few elections. Republicans will win the South and most of the Plains states, while Democrats will win the coasts and everyone meets in Florida and Ohio to battle it out, though Democrats will probably also make gains in the Southwest. For a traditional campaign, Clinton would need a traditional vice president, like Bayh. A two-term governor, a two-term Senator and a former Secretary of State, Bayh's Indiana neighbors Ohio, so many people there know him. Bayh would bring management experience, electoral clout and a polished, skilled demeanor to the stage. He might be a little boring, but many, including Bill Clinton, have said he will one day make a serious run at the White House, something he almost did this year.

Wesley Clark: Clinton would already run strong in Arkansas, a state that voted twice for her husband and twice for George Bush. Clark, an Arkansas native, could tip the state completely into the blue column. Also, Clinton's modus operandi throughout the entire campaign has been to project strength. One way she's done that: Never admitting that her vote for the war in Iraq was wrong, and not apologizing for it. Picking Clark bolsters Clinton in several ways. His military background fills in a resume gap, gives her someone who can credibly argue with John McCain's experience on the war (Having served, like McCain did, is good. Having been a four-star general and Supreme Commander of NATO is better.), and offers her the opportunity to make the case that her candidacy is not of Washington.

Tom Vilsack: The former Iowa governor couldn't manage to stay in the race, but his story is uniquely American: An adopted farm boy goes to law school and works his way up to become governor of his nice Midwestern state -- a state, by the way, that Bush narrowly won in 2004. Geographically, picking Vilsack makes sense, and his Midwestern roots would enable him to compete for votes in Ohio and elsewhere. Vilsack brings management experience and a solid record to the table, and he was an early backer of Clinton's. Though he couldn't deliver his state for her in early January, he worked his heart out, and he's essentially been auditioning for the role for months. The pick would come as close to a surprise without really being a surprise as the candidate could get.

Joe Biden: The only former candidate Clinton could really pick, Biden has foreign policy credentials unmatched by anyone except John McCain. Biden refrained from seriously attacking Clinton in the primaries, something she will surely remember, while offering a serious persona and a hefty resume. He's good in debates, too. His biggest drawback: A complete lack of geographical appeal. Delaware, Maryland and New Jersey will all go heavily Democratic, and while Pennsylvania could, conceivably, be a swing state, if Republicans have a good shot at it Democrats are going to lose anyway. But to contrast a vice presidential pick with McCain, who essentially owns the surge strategy, Biden, whose plan to partition Iraq into three states loosely organized around a federal government, is a pretty good choice.

Longshot: Barack Obama: Clinton does not like Barack Obama, and he seems to have pretty strong opinions about her as well. But if Clinton pulls ahead in delegates by a small margin, she may have no other choice but to offer the number two spot to Obama for the sake of party unity, and to avoid riots on the streets of Denver. Many have speculated for months about what they call a dream ticket, but it has always seemed unlikely that the two would wind up together. Only through force, exerted by some combination of super-delegates, Al Gore and Howard Dean, will they form a ticket. The necessity of such force seems to become more possible every day.

Never Going To Be: Bill Richardson: Speculation has mounted for months that Richardson was running for the sole purpose of serving as Clinton's vice president. But his performance in the race left much to be desired. After two disappointing finishes and too many bad debate performances to count, Richardson stepped aside, grew a Gore-esque beard and went home. His refusal to endorse a candidate doesn't bode well for his chances, and Clinton likely perceived that as an insult. Richardson, once the odds-on choice, now seems a safe bet for a plum ambassadorship or a top posting in the State Department, but little else.

Check back this afternoon for a look at John McCain's choices.