The minute that former vice president Joe Biden officially entered the presidential race, there was an air of inevitability around his candidacy and his spot as the presumptive Democratic nominee. He had the name recognition. He had the nostalgia factor for Democrats yearning for the Obama years. And he was considered more electable in a race against Trump — a vague quality bestowed upon a small circle of candidates who tend not to rock the boat very much. Unsurprisingly, early polls quickly went his way by a wide margin — one that seemed potentially insurmountable.

Electability has always been a tricky concept to nail down. According to Logan Dancey, an associate professor of government at Wesleyan University specializing in Congress as well as elections and campaigns, research and previous election data points to the idea of moderates faring better in many parts of the country. “Historically, especially in congressional elections, candidates with more moderate voting records tend to perform better than candidates with more ideologically extreme voting records,” he explained to Teen Vogue.

There’s also an obvious gender and race component, Dancey said — one that’s harder to grasp for presidential elections since so few women have run for a major party nomination and only one has succeeded in securing that position to date. On top of Biden’s proclivity for more moderate politics, he’s also a wealthy, older white guy — a demographic that has reigned supreme in the political arena since America’s founding centuries ago. His identity is the status quo for U.S. politics, and it’s often up to anyone who deviates to prove they can overcome that norm.

But one of the most important and nuanced — and quite frankly, underrated — trends that strong basic poll numbers mask is how much enthusiasm voters actually have for a candidate. “Enthusiasm is really what is going to drive election numbers,” Elizabeth Simas, an associate professor of political science at the University of Houston who studies electoral behavior and political psychology, told Teen Vogue.

When it comes down to it, the idea that there are a bunch of truly independent voters just sitting around waiting to vote for the perfect Democratic candidate is inaccurate. “It’s activation, not persuasion in elections,” Simas explained. “The likelihood that you’re going to go out and flip somebody from the other party is not high. The number of pure, really persuadable independents out there is not really high. And because of the nature of the electoral college, they would all have to be living in these very particular places that have the potential to swing these elections.” Instead, Simas said, elections are an effort for party faithful to get anyone who’s the least bit inclined toward their side to go out and vote for their candidate of choice — and people won’t do that unless they’re stoked about the nominee.

In the case of Biden, early indicators show that excitement around his candidacy isn’t the strongest, and other candidates who are gaining on Biden are in fact showing a higher level of supporter enthusiasm — and enthusiasm that’s centered around their ideas, not just early poll numbers. For example, in an NBC News/Wall Street Journal poll last month, Senator Elizabeth Warren had the highest amount of Democrats who are enthusiastic about her candidacy at 35%, with another 35% who were comfortable with her candidacy, and only 6% who were very uncomfortable; in contrast, Biden was at 23% enthusiastic Democrats, compared to 41% who were comfortable, and 13% who were very uncomfortable. In a July CBS News poll, among potential Democratic voters in states with early primary and caucus elections, 56% and 54% of them said Warren and Senator Bernie Sanders would fight “a great deal” for people like them, respectively; only 38% of those potential primary voters said the same for Biden. That nuance is lost when we talk about the question of who’s simply winning in the polls and declare that makes them the most electable.