One thing we know for certain is that it won't be a quasi-Republican, weak-kneed, moderate Democrat. Unless Mitt Romney comes riding in on a white horse at the last minute and becomes her opponent, she won't need to kiss up to moderate Republicans. Polls show her doing amazingly well against anyone already mentioned, including Jeb Bush.
Another thing we know for certain is that it won't be Joe Biden. While it's possible he'd accept a position in Hillary's cabinet (Secretary of State or Defense) he's already done his time. Although the job has been depicted, historically, as thankless and puerile, Biden seemed to rejoice in the position. No shrinking violet, it gave him the public platform he coveted. Still, it's a case of "been there, done that."
Here are five choices in descending order of probability.
ELIZABETH WARREN
If Warren is looking for a podium from which to preach her anti-Wall Street reform philosophy, here's a question: Which will get her more attention -- the U.S. Senate, where she's one of 100, or the Vice-Presidency of the United States? Hillary personally likes Liz and would love to turn her loose, allowing her to say things that she, as president, probably can't say.
The obvious downside would be inducing people to vote for two women. Hillary would be our first female president. Ushering in the first woman vice-president on the same ticket might be too much to ask of the non-progressives. On the other hand, for women voters still on the fence, a Sorority Sister ticket might just be enough to sway them.
HOWARD DEAN
He's smart, ambitious, antsy, regretful at not having made more of his earlier (2004) opportunity, and eager to mount another appearance on the national stage. Both he and Hillary come off as preternaturally intelligent, but what she lacks in old-fashioned like-ability and charm, Dean possesses in spades. He's also an M.D., a family doctor. It would be a great pairing.
BERNIE SANDERS
Like Howard Dean, another Vermonter, but unlike Dean, he's a wise and savvy prairie socialist who would give the ticket the necessary "leftwing heft" it requires. His place on the ticket would encourage hope-to-die McGovernites and Ramsey Clark loyalists to vote for a "hawk" like Hillary.
Although Sanders will be 75 years old come election day in 2016, he is physically and mentally fit. Indeed, even at his advanced years, he is arguably mentally sharper than Rick Perry was when he was a fraternity pledge at Texas A&M.
ANTHONY VILLARAIGOSA
Former Mayor of Los Angeles, and perennial political wannabe. His virtues: He's likeable; he's Latino; he's articulate; he's wildly ambitious; and, he's just humble and self-effacing enough to interpret being added to the ticket in order to secure the Latino vote as a "compliment." Also, anyone who failed the bar exam four times can't be all bad.
BILL CLINTON
A bloodless coup. Hillary becomes president. Bill becomes vice-president. Hillary resigns. Bill becomes president. He vows to accomplish in his third term what he couldn't quite finish during his first two.
David Macaray is a playwright and author ("It's Never Been Easy: Essays on Modern Labor").