Who holds the trump card in the Democratic race for president in 2016? Hint: It is somebody that nobody is talking about today.

In 2012, getting Republican voters to line up behind Mitt Romney was like trying to stuff a cat into a trash can. No matter how hard or fast the GOP establishment shoved, voters desperately reached out and clawed onto another candidate — any candidate! — to avoid getting crammed into the trash can with Mitt Romney.

President Obama, who realized he had no business winning a second term, just sat back and smiled. Four years later, the president finds himself watching a very similar situation. Only this time, it is the Democrats who are gagging and recoiling over the cold-leftovers candidate they are being served.

The last time Hillary Rodham Clinton ran for president, all the political experts in all of Washington guaranteed she would get the nomination and be the next president. They were, of course, laughably wrong on both counts. And this time around, they are every bit as cocksure.

All of which is why the polls right now are so gravely alarming to Clinton and her seasoned team of pollsters and strategists.

Socialist Sen. Bernard Sanders, Vermont independent, has surged nationwide, according to the latest Gallup poll, just as Mrs. Clinton’s unfavorability rating is overtaking her favorability rating. In Iowa and New Hampshire, Mrs. Clinton’s unfavorables beat her favorables by double digits!

Ugly, ugly stuff for the Heir Apparent, Take Two. At this point in the race for 2008, then-Sen. Barack Obama was not even winning the black vote in South Carolina, and Bill Clinton was still walking around talking about how he was America’s “first black president.”

But let’s be honest, as rough as it looks for Hillary Clinton right now, it is still fairly unimaginable that Bernie Sanders could win the nomination, even for the increasingly socialistic Democratic Party.

And ex-Maryland Gov. and former Baltimore Mayor Martin O’Malley is clearly way out of his depth. The city he ran for years was literally on fire a few months back and remains a powder keg of angry dissatisfaction with all the false promises of modern liberalism (socialism). And he was such a terrible governor that voters in one of the bluest states in the nation leapt into the arms of a Republican first chance they got.

So who does hold the trump card for Democrats? Who is the one Democrat who could keep all of Hillary Clinton’s supporters and mop up all the voters dissatisfied with her — all the while remaining at least marginally acceptable to the broader American electorate?

Only one man: Joseph R. Biden.

And what makes this all the more intriguing is how curiously silent Vice President Biden and President Obama have been lately about the 2016 race. Are they quietly plotting a way for President Obama to stun the political world and go all in behind a Biden candidacy?

There are many, many reasons this ruthless president would do such a thing.

It would allow the president to finally make good on the initial galvanizing promise of his 2008 campaign. He would finally seize control of the Democratic Party and take it away from the Clintons. Forever.

Secondly, it would allow the president to keep his coalition of voters together. Black voters, especially those involved in the volatile “Black Lives Matter” campaign, are vocally and vehemently dissatisfied with Mrs. Clinton. Mr. Biden, with help from Mr. Obama and the right campaign, would have a real shot at keeping those voters together and engaged.

Thirdly, publicly rebuking the Clintons would be rich payback for all the disgusting shenanigans they pulled on President Obama after he extended such an extraordinary and unexpected and undeserved an olive branch as he did when he made her secretary of state.

All the sleazy dealings, donations and paid speeches on behalf of the Clinton Foundation and the massive bungling of Benghazi, and now the constant scandals surrounding the secret email servers. In one fell swoop, President Obama could at least appear to restore his promise of the most transparent presidency ever.

And I remember eight years ago, when Mr. Obama’s top campaign hands, who went on to top jobs in the White House, assured me that the one person Mr. Obama would never pick for his veep is Joe Biden.

Well, he did. And for a reason.

For all of Joe Biden’s bloopers and goofy gaffes, people tend to like him. Few people doubt that Mr. Biden loves America. He is deeply patriotic about how the government works; he would be respectful of congressional authority. And, most importantly, he loves people and campaigning.

For all of these reasons, Mr. Biden was a soothing influence on a presidential ticket that otherwise seemed alarming and radical to so many.

And once again, Joe Biden could be that calming influence.

Charles Hurt can be reached at charleshurt@live.com and on Twitter via @charleshurt.