It was so much fun last time, let's do it again. Photographer: Ken Cedeno/Bloomberg  
It was so much fun last time, let's do it again. Photographer: Ken Cedeno/Bloomberg  

Hillary Clinton will face a challenger for the 2016 Democratic Presidential nomination, if she runs, for a simple reason: everyone always has.

Several people close to the former secretary of state place the odds of her running at 80 percent or greater; she would be the strongest non-incumbent front-runner in modern American politics. She may well be unbeatable for the nomination but someone will try -- either from the ideological left or to position themselves for a future try.

Some politician "will take a flyer,' says David Plouffe who directed President Barack Obama's presidential runs. Plouffe believes there's "very little oxygen" for a serious challenge to Clinton; the appeal is "their moment on the debate stage or getting 30 percent in a state somewhere."

Of course, Vice President Joe Biden insists he's keeping his options open, and privately sounds like he's running. Few high-level Democrats think he actually would if the former New York senator runs. Biden sought his party's nomination before -- in the 1988 and 2008 cycles -- and had to drop out early.

One Democrat who has flirted with the idea is Martin O'Malley. The 51-year-old Maryland Governor, whose term expires this year, might see an opportunity to set a predicate for a future run.

The other possibility is a challenge from the left. Hillary Clinton is relatively hawkish on national security and is a favorite of more than a few on Wall Street. Brian Schweitzer, former governor of Montana and a sharp critic of the Obama administration, has mused about a run from the populist left, calling for a single-payer system to replace Obamacare and to crack down on national security surveillance on Americans. That path also could appeal to Vermont Senator Bernie Sanders, a socialist.

The favorite of the left would be Massachusetts Senator Elizabeth Warren. It's virtually certain, however, that neither she nor any other prominent Democratic woman would challenge Clinton -- they are agreed that 2016 is the moment to elect the first female president and want to clear the way for the most likely history-maker.

And, political operatives who've worked at the top level of Clinton campaigns say, it'd be a fool's errand to run in order to be her running mate. Yet they, like Plouffe, agree if she runs she'll have primary opposition.

There may be free lunches in politics, not free rides.

To contact the writer of this article: Al Hunt at ahunt1@bloomberg.net.

To contact the editor responsible for this article: Tobin Harshaw at tharshaw@bloomberg.net.