The Democratic debate held in Los Angeles Thursday night provided some of the most intense clashes of the 2020 race for the nomination to date. Unfortunately for Pete Buttigieg, the one that best lent itself to a trending Twitter hashtag was Elizabeth Warren’s putdown of a lavish fundraiser he recently held in a #winecave.

Beyond the damage that does his campaign, the exchange is indicative of a paradoxical challenge facing the 37-year-old South Bend, Indiana, mayor: The youngest major Democratic candidate, who has called for a generational change in leadership, isn’t resonating with the youngest voters. And one of the reasons is that his high-brow hobnobbing is a sign of a politics-as-usual approach that doesn’t appeal to his own millennial peers.

Why isn’t he the one for millennial and Gen Z voters? Because it seems that for these generations, a candidate’s youth alone isn’t enough to signify real change or shared identity.

Buttigieg trails the oldest candidate, Sen. Bernie Sanders of Vermont, by 41 years and 11 percentage points, according to the RealClearPolitics polling average as of Thursday night. His gap is similar with 70-year-old Warren, a Massachusetts senator. But among the youngest voters, his numbers are far worse. While his RealClearPolitics average is at 8.3 percent of national support, a Quinnipiac University poll last week indicated that only 2 percent of voters ages 18 to 34 would support him, compared to 12 percent of voters ages 35 to 49 and 50 to 64, and 11 percent of voters over 65.

The age dynamics in the Democratic race fly in the face of several streams of classic research on the roles of age and similarity in choosing our leaders. Traditionally, voters tend to gravitate to candidates they perceive as being “like them,” including younger voters’ showing a preference for younger candidates. Research also shows that we tend to look to younger leaders when we want change and older ones when we want stability. Given the surge of potential young voters in 2020 and the Democratic push for change, Buttigieg seems an obvious choice.

So why isn’t he the one for millennial and Gen Z voters? Because it seems that for these generations, a candidate’s youth alone isn’t enough to signify real change or shared identity. It’s another way that younger Americans are shaking up conventions, and that has a consequence for a fairly conventional candidate like Buttigieg.

Running primarily on a moderate platform, Buttigieg doesn’t represent the bold change agent whom younger voters are hoping for in 2020. Instead, they prefer Sanders and Warren because their more progressive stances represent a deeper contrast with the status quo.

The Midwest mayor’s tone and incremental approach on issues they agree on could also be stumbling blocks. Younger voters are eager for big transformation, particularly on issues like climate change, gun control and racial unity. Buttigieg has plans to address these issues, but he has cautiously framed them as “careful” promises.

Buttigieg has fared better with older voters, however. To his elders, Buttigieg does represent change; he’s younger than a "typical" president has been (the youngest president ever elected was JFK, at 43, five years older than Buttigieg is now), and he's also openly gay, which to older generations may seem progressive and could reach the degree of change they are looking for in 2020.

For younger generations of voters, though, he lacks authenticity. That quality — a belief that leaders will do what they say they will do and that their actions align with their core values — is critical to developing trust in leadership.

Buttigieg’s attempts to connect to younger voters have largely fallen flat because they aren’t perceived as authentic, as he is young but doesn’t stand where millennials and Gen Z do on the political spectrum. A Washington Post writer also has also posited that his eager-beaver acquisition of traditional credentials is a factor — the very qualities that would lead one to hold an exclusive fundraiser in a wine cave, whatever that is.

A similar dynamic is clear from research I conducted in 2016, which found that while millennials, Gen X and baby boomers all cared about expertise and character when judging the credibility of a leader, millennials significantly valued one thing much more than older generations: leaders’ ability to strongly connect with and relate to their followers.

Here we find yet another paradox for Buttigieg. We would expect him to be the candidate with the most social media savvy, but looking at popular social media channels, Buttigieg struggles compared to his older competitors on every one.

Millennials and Gen Z will be a crucial force in the 2020 vote, making up 37 percent of eligible voters. Which makes Buttigieg’s struggles with this demographic group a major liability. It’s gotten so bad that he recently brought in a “national youth engagement director” to help with his campaign.

In March, Buttigieg pushed for generational change, stating, "We need more voices stepping up from a generation that has so much at stake in the decisions that are being made right now." It looks as though the younger generational voices he called for are indeed stepping up — but they are looking for someone else to bring the pivotal transformations they seek.