On Monday, I made the case that Al Gore should run for president. But there's another obvious contender out there, too: Joe Biden.

Over at Yahoo, Matt Bai makes the case for Biden. "Biden," he writes, "is a better candidate than most pundits have ever given him credit for. Yeah, he's sloppy and meandering and says some nutty stuff. But that's all part of being genuine and three-dimensional, which may be the most valuable trait in modern politics and not a bad contrast to Clinton's robotic discipline."

And Biden's certainly got the resume. When President Barack Obama wanted to make sure stimulus money didn't disappear to fraud, he turned to Biden — "nobody messes with Joe," he said — and Biden succeeded. When the White House wanted to avoid the fiscal cliff, it was Biden who closed the deal with Minority Leader Mitch McConnell. When Obama flubbed the first debate against Mitt Romney, it was Biden who restored the ticket's mojo by bullying his way past Rep. Paul Ryan. When the Democrats held their 2012 convention, it was Biden's speech that pulled the highest ratings — beating both Bill Clinton and Obama.

Biden's most off-the-reservation moment, meanwhile, is the kind of thing that should help him in 2016. He pushed the Obama administration to embrace gay marriage before it was quite ready. At the time, it looked like a gaffe. Now it looks prescient.

And yet, according to a recent Marist poll, Biden is running 47 points behind Hillary Clinton for the Democratic nomination in 2016 — and only one point ahead of Sen. Elizabeth Warren. A quick scan of RealClearPolitics' round-up of Democratic primary polls shows that's no outlier.

It's not like Biden has been out of the public eye for the last seven years. So why, if he's such a good politician, doesn't he command more support in the Democratic Party?

Here's my guess: there's a cultural gap between Biden and the party he seeks to represent. Biden is an old-school, white, male politician in a party that's increasingly young, multicultural, and female. Biden's gaffes matter because they tend to reinforce the perception among Democrats that he belongs to a different era.

When Biden calls shady lenders "Shylocks," or says Obama is "the first mainstream African-American who is articulate and bright and clean and a nice-looking guy," he ends up coming off as, in New York Magazine words, "your accidentally racist grandma." That leaves Biden facing something more toxic than opposition: condescension.

What I wrote of Biden in January 2013 is still true today, I think. "In the continuing drama that is the Obama presidency, Biden often appears as comic relief. He's the zany neighbor, the adorable uncle. As a result, his presidential ambitions, which burn brightly even today, have mostly been laughed off. Somehow, the sitting vice president of the United States, the former chairman of both the Senate Foreign Relations Committee and the Senate Judiciary Committee, a man who's on a nickname basis with many of the world's most powerful leaders, is seen in many quarters as lacking the gravitas to be president."

There is much that's weird about this. Hillary Clinton is a powerful candidate, but there's nothing about the last few months that makes her look invulnerable. She's shown real rust in interviews, pissed off liberals, and found herself in an email scandal.

But while Biden isn't much older than Clinton, she's somehow been more adept at signaling cultural affinity with young Democrats than he's been (though she's occasionally struggled too, most notably in her interview with Terry Gross on gay marriage). She also has a connection to female voters he can't touch. Even her memes are better.

I don't know exactly how Biden fixes this or even if he can. Clinton isn't inevitable, and Biden should, by all rights, pose a real threat to her. But, though Biden's always been known as a great speaker, he needs to learn to talk to a different party than the one he grew up in.