WASHINGTON -- Let's say Hillary Clinton glides into Iowa with no serious opposition -- as seems likely. Then, on the night of the caucus, she gets only 70 percent of the vote. Or maybe 60 percent. Or even 55. Is that a victory? Clinton could become the first person to "lose" a primary with a majority of the votes. That's because she can't merely win the actual vote: She needs to beat expectations.

A presidential campaign is a series of smaller, interrelated contests -- the state competitions themselves, of course, but also the Fundraising Primary, the Beltway Primary, and the Expectations Game. Or at least that's how the media covers it, which can become a self-perpetuating cycle of  "What's Wrong with Hillary?" headlines.

As the undisputed frontrunner, Clinton must find a way to avoid any perception that she's weaker than she should be. To do that, she needs to manage expectations, keeping them low enough that she can appear to exceed them, but high enough to discourage real challengers from jumping in or big donors from wandering off.

“The expectations game may actually be the only game in town on the Democratic side. With the nomination contest not much of a race, Hillary's percentages in the states are the only way to judge the degree to which Democrats are embracing her candidacy,” University of Virginia political science professor Larry Sabato said. “Get ready for some masterful spin. Without damaging Clinton's image of inevitability, Hillary's campaign has to build up even minor opponents.”

Here's a prime example of how that's done: Virginia Gov. Terry McAuliffe, who chaired Clinton’s campaign in 2008, responded to a question recently about how well she will need to do in early primaries by building up the prospects of possible opponents.

“Clearly, there are going to be candidates running, don’t assume,” McAuliffe said. “Sen. [Jim] Webb has indicated interest. Sen. [Bernie] Sanders has indicated interest. I’m sure we’ll have some lively primary action.”

In addition to Sens. Webb and Sanders, former Maryland Gov. Martin O'Malley seems to be contemplating a run. So there will likely be other names on the Democratic ballot in 2016 along with Clinton's -- even if some candidates are running mainly to increase their national name recognition or boost their chance to be chosen as Clinton's veep.

If no other Democrat runs? That would be extraordinary. There hasn’t been a primary race in modern history where someone other than an incumbent office holder or sitting vice president sailed uncontested to the nomination. Even Al Gore saw some competition from then-Sen. Ben Bradley. “This is really something new,” Aaron Crawford, a presidential historian at Southern Methodist University, said. “It may be unprecedented in modern politics.”

Clinton in any case is the overwhelming favorite. By this time in the 2008 race, then-Sen. Barack Obama had a substantial fundraising and on-the-ground apparatus in place, and former veep candidate John Edwards was also seen as a strong challenger, one who had spent months wooing voters in Iowa. No other putative Democratic candidate has anything approaching Clinton's advantages. She is in a commanding position.

And that's the problem. In 2008, the bar was easy to set: Get more votes than anyone else. Clinton won New Hampshire with 39 percent of the vote -- far from even a simple majority. And it was heralded as a monumental win for her.

When there's no real opposition, even fringe candidates can disrupt the narrative.

In the 2012 Democratic primaries, incumbent President Barack Obama was running unopposed. But in West Virginia, convicted felon Keith Russell Judd, serving time in a Texas federal prison, got his name on the ballot. He took 42 percent of the state’s vote and Obama lost 10 counties.

The backlash was immediate. It prompted questions about an "enthusiasm gap" and fueled concerns about whether Obama could survive the general election.

Clinton could easily face a situation where she failed to carry 100 percent of the vote. There is no ballot in Iowa; voters show up and can caucus for whomever they want. If a movement to draft Elizabeth Warren hasn't been put to bed, for example, a grassroots group could organize an effort to caucus for her. And the caucus process in Iowa is two steps. Unhappy Democrats could first vote for someone other than Clinton and then move to the inevitable winner on the second count. Only the last count matters, but with the press watching closely, public displays of dissatisfaction with Clinton wouldn't go unnoticed.

David Redlawsk, a pollster at Rutgers University who previously worked at the University of Iowa, said Clinton needs to start energizing the party base.

“One of the serious risks that you face is that the disaffected wing of the Iowa Democratic Party will come out and caucus for Elizabeth Warren even if she’s not a candidate, or Bernie Sanders even if he’s not a Democrat,” Redlawsk said. “It would be a PR problem for Clinton if she came out of Iowa being the only candidate but getting only 75 or 80 percent.”

Joe Trippi, who has worked on several presidential campaigns including John Edwards' 2008 run, argued that if there's no competition on the Democratic side, there will be more attention paid to GOP jockeying.
“What it does is put a lot more focus on the Republican fight and who’s going to be [Clinton's] opponent,” he said. “The media wants a fight, they love a fight. And if there isn’t one on the Democratic side, then that puts more heat on the Republican fight, not on trying to create something out of nothing with Hillary.”

Still, he said, “I think she would benefit from going through a primary challenge.”

Facing a strong opponent could, paradoxically, make the race easier for Clinton. Of course, it might also present the risk of actually losing. Compared with that, being merely a disappointment starts to look pretty good.