Imagine, for a moment, that it were President Donald Trump on Instagram live, broadcasting from the White House kitchen, with his classic red tie loosened and his standard white dress shirt unbuttoned as he reached for a longneck beer to crack open mid-sentence.

The image is difficult to conjure.

Aside from the fact that Trump doesn't drink alcohol, he likely hasn't fetched his own beverage from a refrigerator in decades. ("Get me a Coke please," he was heard saying on a recorded conversation with his former attorney Michael Cohen.)

Trump doesn't do "interactive" conversations. He barks promises and demands. Trump's not warm and fuzzy. He's tough and threatening. So any picture of the president attempting to play down home and folksy wouldn't sell. It would be dubbed fake, phony. Inauthentic.

Elizabeth Warren's first week as a presidential candidate included a venture onto Instagram live, the streaming function on what's currently the coolest social medium for politicians to play with.

But when the Massachusetts senator paused mid-sentence in her kitchen to snag a Michelob Ultra – "I'm gonna get me a beer," she declared – it stirred up barroom conversations across America: Was she being her true self? Does the real Elizabeth Warren regularly crack open brewskis? Is she ... authentic?

CNN's Erin Burnett wasn't buying the tab.

"This is a woman who is a professor at Harvard Law School and she gets on camera in the past week and goes, 'I'm gonna get me a beer.' Let me just say, that to me is completely inauthentic because that's clearly not the way a Harvard law professor speaks," Burnett declared Friday night on her program.

"Authenticity, it's all about authenticity. That's a big deal to voters," clamored Stephen Moore, the Republican on the panel.

"I didn't find it inauthentic, no," liberal pundit Joan Walsh intervened. "The woman is from Oklahoma."

"You don't think it was authentic," she said to Burnett. "I think it could be."

The moment was a small one, given everything else Warren accomplished in her first week, including staffing hires and a largely successful first venture to Iowa. But it points to a larger question that all Democratic presidential candidates are going to face in the coming months: how to stay true to yourself while acceding to the demands of voters in a hyper-connected, interactive, Instagram age, when simply performing on the campaign stump isn't sufficient.

Coming off as "genuine,' "real" and "regular" has been essential to a White House candidate's success for almost as long as campaigns have been run. Recall the fuss over George H.W. Bush's handling of the supermarket scanner and Michael Dukakis cruising in a tank nearly 30 years ago.

Jokes aside, apart from electability, some Democrats see authenticity as the most crucial ingredient for their nominee to embody this time in order to be successful against Trump.

"The real question for me isn't who's left, left of center – it's all nonsense," says Tom Nides, a former deputy secretary of state and longtime Democratic donor. "Elizabeth Warren's voting record is the same as Amy Klobuchar's or Kamala Harris' or Sherrod Brown's. For the most part, everyone's voting record is the same. What people have got to focus on is one word, the key word: authenticity. That will be the definition of who wins."

Authenticity has been the central ingredient fueling the rise of Beto O'Rourke , the formerly little-known former Texas congressman who amassed a movement in his sunny-eyed closer-than-expected challenge to GOP Sen. Ted Cruz last year. Jim Messina, President Barack Obama's former campaign manager, described him as "authentic, and luckily, authentically cool."

Almost every analysis of O'Rourke – now a burgeoning 2020 White House contender – includes a nod to his "authenticity."

He fostered that trait early on in his upstart Senate bid with an unorthodox approach that dedicated hours to Facebook live broadcasts from places the public doesn't usually see their politicians – hovering over laundry and skateboarding through a parking lot.

It worked because it was unfiltered but also because it showcased him in far-flung conservative counties most political consultants would tell him he had no business campaigning in.

"You didn't see him as a congressman very often," notes Amanda Renteria, the national political director for Hillary Clinton's 2016 campaign. "It was on the road, somewhere."

"And doing it in such a way where it's not on a stage with a microphone all the time, but it's in a burger joint or on a run."

Because of the fame his approach garnered, O'Rourke is now formally mulling a presidential campaign. A draft movement has even spawned to nudge him to "yes," which the backers argue is yet another dynamic that enhances his authenticity.

"All these other candidates have been closely eyeing the presidency for two years, and I think they're slightly tainted by that fact," says Nate Lerner, co-founder of the Draft Beto group. "With Beto, people are calling him to do it. He seems hesitant. To have him be dragged into this race, I think adds authenticity to him."

But there are limits to such "authenticity." When O'Rourke posted video of his dental visit to his Instagram story on Thursday, even some of his supporters found the stunt to be a bridge too far.

"Love me some Beto, but this is self-parody territory," tweeted Ana Marie Cox, a liberal columnist.

Sen. Cory Booker of New Jersey, another likely White House aspirant, will undoubtedly face authenticity questions if he runs, given his flair for dramatic rhetorical acts. His "I am Spartacus" outburst during the Brett Kavanaugh Supreme Court confirmation hearings was widely mocked by Republicans and induced considerable eye-rolling among Democrats.

Booker has been open about leading with his heart, in a visceral and emotional way.

"My closest friends say to me, 'When I have conversations with people, they ask that question: Is he for real?' Which I don't understand. 'Is he real?' 'Is he for real?' I don't understand where that question really comes from," he confided to New York magazine.

Obama strategist David Axelrod has said the senator sometimes "sacrifices a sense of authenticity" for "performance." A Democratic consultant for a potential 2020 rival was more explicit in his Booker assessment: "He's kind of a phony. People can see through his act."

Authenticity, of course, is in the eye of the beholder, which in this case will be the voters in the earliest nominating states.

Sen. Bernie Sanders of Vermont wins authenticity points for eschewing "likeability" altogether. Like Trump, he has a message to deliver in a clamorous, crotchety way that largely disregards empathy or "feeling your pain."

"Bernie is everything Warren is but better," CNN's S.E. Cupp said last weekend. "He is more energizing, more unifying and certainly more authentic."

Former Vice President Joe Biden has stockpiled years of "authentic" bona fides from his trips taking the Amtrak train to Washington to his series of off-script "foot-in-mouth" remarks that land him in hot water politically and yet endear him to the masses.

The New York Times recently noted Ohio Sen. Sherrod Brown's Cleveland-made suits, usually adorned with a canary pin from a steelworker, as evidence of "grizzled authenticity."

For female contenders though, like Warren, properly defining authenticity is always a dicier proposition, given that far fewer women have run for president and that their credibility can be evaluated through a lens not always equally applied to men.

Christina Reynolds, the top communications operative for Emily's List and a veteran of the 2016 Clinton campaign, cheered Warren's beer gulp – "You earned your beer sister," she says – and observes that Sanders has never been penalized for not being likeable enough.

"I think it is a cudgel used against women. Women are supposed to be likeable, and that's supposed to be a part of their authenticity. Whereas men can be authentic without being likeable," Reynolds says. "Only you know if you're being authentic. Voters don't actually know. It's a matter of what they think."

And what's observed as "authentic" to one person could be seen as "unpresidential" for another.

The petty kerfuffle over an old video of Rep. Alexandria Ocasio-Cortez dancing reminded Renteria of the concerns around Clinton's delicate image on the campaign trail.

"I remember when Hillary was dancing on the stage with El Gordo. There were questions about whether she should've been doing that," she recalls of a 2016 visit the candidate made to a Spanish-language television program on the Univision network. "A woman dancing somehow brings down her credibility, yet when we saw older guys dancing we thought it was cute and interesting. Look at Obama shaking his shoulder!"

Renteria forecasts that 2020 will demand more accessible moments from contenders than even in 2016 and that candidates will have to experiment with what works best for them without doing things that are painfully uncomfortable and awkward.

Often, the moments that reveal the most genuine flashes of authenticity aren't the staged Instagram beer, but the completely unplanned interaction, sometimes even behind the stage before or after an event without a camera in sight. That's why the truly raw, unmanufactured occasions that are captured are so rare.

Renteria's advice is for candidates to constantly explore different ways to connect "on things that are real for people" but to resist forcing something that's not really in one's character.