If Hillary is the Democrat nominee, who might her VP be? Does it really matter?

[Mister Mets]

Toying with a Top 16...

16) John Hickenlooper-
The main negatives are that he's older, divorced and in a surprisingly tough reelection fight. But a swing state Governor is always going to be considered.

15) Sherrod Brown-
Also over 60, but the base likes him, and he's the Democrat's best bet in Ohio.

14) Charlie Crist-
If he wins another term as Governor of Florida. He helps in a crucial swing state, and allows Hillary to hammer a message about how Republicans have gone too extreme.

13) Anthony Foxx
Former Mayor of Charlotte, North Carolina. Secretary of Transportation.
Can help with African-American turnout, campaign in North Carolina, and be a surrogate on an issue that's important to voters: smart infrastructure spending.

12) Martin O'Malley
Bland, but ready Governor.

11) Gavin Newsom
A western male under fifty who backed Hillary in '08. Progressive bona-fides as former Mayor of San Francisco. Practice as the #2 as the Lieutenant Government to Jerry Brown.

10) Martin Heinrich
Young western Senator.

9) Terry McAullife
One of Hillary Clinton's best political allies became the Governor of a swing state. Why on Earth wouldn't she consider him a potential veep?

[Mister Mets]

And the top half...

8 ) Steve Bullock-
Youngish western Governor. Had the political chops to win an election in a state Obama lost by over 13 points. Montana is a very small state, but at least he'll be in the end of a full term.

7) Xavier Becerra
He's a qualified Hispanic politician who can help Hillary with the Congress, and is comfortable in front of cameras.

6) Cory Booker
Young media-savvy Senator. Can excite younger voters, and help with African-American turnout.

5) Tim Kaine
Has won three elections in a key swing state. Executive experience as former Governor. Already been a party surrogate as former DNC Chairman. And he'll have four more years as Senator (meaning he could help Hillary's relationships with Congress, considering all the Senators who have served after she left.)

4) Julian Castro
By making him HUD Secretary (a position held by a former Republican VP candidate) Democrats basically built a potential running mate for Clinton, taking Castro's top liability (limited experience as part time Mayor) off the table. He's a young Hispanic guy who is also the protege of Clinton buddy Henry Cisernos (another San Antonio Mayor/ HUD Secretary.)

3) Mark Warner
Has many of the strengths of Tim Kaine, but greater political gifts and private sector experience. And he's more popular in Virginia.

2) Anthony Brown
An African-American who backed Clinton over Obama in 2008, and is likely to get elected Governor of Baltimore. His civil rights background can impress progressives, and his military background pleases the center. He also has practice being in the #2 spot as O'Malley's veep.

1) Michael Bennet
Hillary Clinton's ideal running mate would be a younger male Senator (Senators are more familiar with national issues, and can help govern later) from the west with policy chops on a major issue. Bennet will be in his early 50s, and has been the Superintendent of the Denver Public School System. And he comes from the state where Hillary Clinton has the most trouble. And he proved his political chops getting elected to a full term (difficult for appointed Senators) in a bad cycle for the party. I think he has a slightly better shot at being the running mate than anyone else.

[Mister Mets]

I'd love it if Hillary Clinton picked someone who doesn't currently have a wikipedia page as her running mate, especially if they don't do anything in the next two years to become more prominent.

That would be a rare case in which the Veep nominee matters a lot.

[Mister Mets]

The last part of the thread question hasn't been touched on. How much does it matter who is chosen to be the veep?

Veeps mainly matter in close elections. If Clinton/ Castro win by eight points in the popular vote, Clinton/ O'Malley would still have won.

Even in close elections, a running mate isn't always significant. If Bennet helps Clinton narrowly win Colorado, but she loses Florida, Pennsylvania and Ohio, it won't change the outcome of the presidential election.

The main effect a veep could have is negative. If vice presidential nominee Tim Kaine starts talking about reparations, Democrats would get very nervous. If vice presidential nominee Paul Davis thinks Isis is a country in Europe, that would be an awful news cycle.

There are other campaign considerations. If Clinton gets along well with the running mate, that can make a small difference, but there will be much more important factors.

[Mister Mets]

I'd agree that Bennett would be her best choice, but as has already been pointed out, he'll probably be out of contention due to likely facing a competitve reelection campaign.

So I guess Warner or Kaine would be the frontrunners. Heinrich or Brown could be possibilities but we'd probably lose their seats because Martinez and Kasich would likely be the ones respectively appointing their replacements.

I could see Tester or Merkley being dark horses.

I'd imagine that Democrats would decide it's worth risking/ losing a Senate seat to get the best Vice President.

Obama considered Tim Kaine a potential running mate even though it would have elected the Republican Lieutenant Governor. He appointed Janet Napolitano Secretary of Homeland Secretary even though it meant Jan Brewer became Governor.

Republican Governors may not want fights over replacing someone from their state who has just been elevated to national office.

[Mister Mets]

The main way a veep would matter a lot in a positive way would be if they really hurt the other side's credibility. For example, if John McCain had agreed to be Kerry's running mate in 2004.

There aren't many prominent Republicans with that level of name recognition, but if a Brian Sandoval or Rob Portman agreed to be on a unity ticket with Hillary because of their objections to the Republican nominee, it would be a big deal.

It's highly unlikely for all the reasons we don't see unity tickets, but this would be something that matters.