DAVENPORT, IA - JULY 17: New Jersey Gov. Chris Christie listens to speakers at 'An Evening at the Fair' event with Scott County Republicans in the Starlight Ballroom at The Mississippi Valley Fairgrounds on July 17, 2014 in Davenport, Iowa. In addition to the event at the fairgrounds, Christie attended two fundraisers for Iowa Gov. Terry Branstad and Lt. Gov. Kim Reynolds and greeted patrons with them at MJ's Restaurant in Marion, Iowa. With this four-city Iowa tour many suggest Christie may be testing his support in the state with hopes of a 2016 Republican presidential nomination. (Photo by Scott Olson/Getty Images)National Journal

One of the most underappreciated attributes in politics is a candidate's authenticity. In an era when politicians' talking points are scripted, and they worry about a gaffe going viral, the candidate who comes across as genuine holds a real advantage. It's one reason why Barack Obama was able to defeat Hillary Clinton, why Mitt Romney struggled to capitalize on a favorable environment in 2012, and why someone like New Jersey Gov. Chris Christie is able to use his force of personality to overcome ideological differences with both Democrats and conservatives.

And the authenticity factor has played a critical role in this year's midterm elections, from the challenges red-state Democrats face in winning over skeptics to the problems establishment Republicans have faced in reaching out to the tea-party grassroots. Just take a look at the successful and flailing candidates this cycle, and a lot of the gap comes down to authenticity.

It's a worrisome sign for Senate candidate Michelle Nunn, whose campaign was roiled this week by the revelation of a months-old internal campaign memo that offered frank advice on what it would take to win in Georgia, a conservative-friendly state. The memo, reported by National Review's Eliana Johnson, portrayed a candidate with few core values, relying on friendly photo-ops to reassure rural voters and willing to take positions that would raise her the most money. Nunn's stance on Israel, for example, was "TBD," but her advisers strongly recommended taking a supportive position, thanks to "tremendous financial opportunity" in the Jewish community.

For those who are involved in politics, the memo wasn't particularly shocking—it's part of the currency of all campaigns. But the details in it illustrate the dilemma for Democrats running in conservative states, whose true beliefs probably run counter to a majority of their constituents. That's been a running theme this election with first-time Senate candidates, such as Nunn and Alison Lundergan Grimes in Kentucky, who have assiduously avoided offering policy specifics in favor of bland generalities. Staying on message is akin to lacking any type of message.

When Grimes struggles repeatedly to articulate her views on border security, it's clear she's caught between exciting the Democratic base, the source for her impressive fundraising, and winning over moderate voters in Kentucky. When Nunn says she would have voted against Obama's health care law but avoids talking about any changes she'd make to it, it's easy to assume she's trying to do everything she can to have it both ways. Unless Democrats have a clear record otherwise (see: Manchin, Joe), it's going to be hard for voters to find them believable.

Republicans have a similar authenticity challenge, one that's been manifesting itself in primaries. Call it the Eric Cantor challenge. The outgoing House majority leader's loss to a little-known professor was driven by numerous factors, but the one unifying theme was that he wasn't who he presented himself to be. He represented a Richmond district but spent much of his time in Washington and in the Hamptons. He initially positioned himself to John Boehner's right in leadership, but later helped vanquish the conservative rebels to end the government shutdown. His recent support for legislation allowing young illegal immigrants to become citizens convinced constituents that he supported immigration reform, despite his public opposition. All this, over time, raised enough suspicion that he lacked core beliefs, other than the pursuit of power.

While the Democratic Party has become increasingly liberal over the years, making it harder for their red-state candidates to survive, the battle within the Republican Party is between the elites and the grassroots. The Pew Research Center, in its annual political typology, found the divide within the party to be between conservatives who are "socially conservative populists" and business-minded conservatives who are "pro-Wall Street and pro-immigrant." The former make up a narrow majority of Republicans, but most of the party's leadership fits in the latter category.

So while the roots of most primary challenges this year are ideological, many stem from the perception of inauthenticity. In Kansas, conservative critics of Sen. Pat Roberts have focused more on the fact that he's rarely in his home state than on his difference with challenger Milton Wolf on particular issues. Sen. Thad Cochran of Mississippi struggled when he tried to out-conservative Chris McDaniel in the primary, but the veteran appropriator shined in the runoff, when strategists refocused his message on bringing home countless benefits to his constituents—a subject that came naturally to him.

Meanwhile, the battle over authenticity is raging in many of the key general-election races. In Iowa, Republican Joni Ernst emerged as the star recruit of the cycle because of her candid account of "hog castration," while her Democratic opponent, Bruce Braley, has been embarrassed by undercover video that's at odds with his carefully tended image of being farmer-friendly. In Colorado, one of Democratic Sen. Mark Udall's biggest assets is that he looks out of Rocky Mountain-central casting, with his Patagonia jacket and with the state's mountain peaks and streams playing supporting roles in his advertisements. (One adviser said he thought Udall's avid mountain climbing would be an asset in Colorado, one of the most fitness-friendly states in the country.) In a battleground New York House race, wealthy venture capitalist Sean Eldridge, a Democrat, has struggled to convince voters in the rural Hudson Valley district that he's one of them—despite having deep pockets and running in a district that Obama carried twice.

GOP Senate candidate Tom Cotton famously—and awkwardly—said, "I'm warm, dammit!" when asked recently about his attempts to relate better to Arkansas voters. But in this environment, being charismatic isn't as important as being real. With cynicism toward politics endemic, being able to convince voters you mean what you say is an asset that shouldn't be underestimated.

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.