The power of Philly’s voting blocs keeps shifting. Who will determine the next mayor?

When Philadelphia voters voice their pick for a new mayor next month, the outcome will depend in part on the influence of the city’s various blocs of Democrats. The strength of these groups shifts from election to election — and this year is no different.

“You don’t need the whole city to be behind you,” said Joe Pierce, the Philadelphia-based state director for Sen. John Fetterman. “It’s more about, how can I turn out enough of my people to carve out just enough votes?”

And that math is always evolving as demographics and political dynamics change.

Based on past primary voting habits, The Inquirer identified six groups of Democrats in Philadelphia — all essential to the city’s politics, but unequal in size and influence — who will vote in the May 16 primary:

Every voter’s preference matters, but those preferences tend to correlate within groups. And the sway of those groups depends on three interrelated factors:

All three of those factors together help determine who wins. For example, a group can be united behind a candidate but contribute relatively little to the overall vote because of small size or low turnout. Or a group that turns out in big numbers but divides its vote among multiple candidates can squander its influence.

» READ MORE: We used an algorithm to find the six kinds of Philly Democrats who vote in mayoral primaries

The smallest cluster of precincts is the one made up of wealthy white liberal precincts, accounting for just 10% of the city’s registered Democrats. But they consistently punch above their weight.

This is the richest and best-educated cluster, both characteristics associated with high rates of primary voting. True to that, the “super voters” in this cluster — who turn up election after quiet election — average 13% of the citywide vote.

Voters here are often highly informed and actively seek out information about politics and voting.

“They’ve basically made up their mind,” said Philadelphia-based political consultant Joe Corrigan, who is not working with any of the campaigns. “And they’re making it up based on what they’ve read, what they know, what they see in the news.”

And that influence is growing. Between 2010 and 2020, the adult population in this cluster grew by 26%, the greatest among the clusters. That growing population is reflected in its share of the city’s vote, which has increased substantially.

Still, the cluster’s overall size limits its voting power. But this group is influential in other ways, such as by being a source of funding. Four mayoral candidates live in this cluster, the highest of any grouping.

This group generally votes together for establishment candidates. They supported Mayor Jim Kenney in 2015 and 2019 and Hillary Clinton, Josh Shapiro, and Katie McGinty in 2016 for president, attorney general, and U.S. Senate, respectively — all by wide margins.

The second-smallest cluster, the group of poor voters and Latino voters, is similar in size to the wealthy white liberal cluster, constituting just 11.5% of the city’s registered Democrats.

But they lie on the opposite end of the spectrum of political engagement. This group has disproportionately low influence: It hasn’t broken 10% of the overall Democratic primary votes at any time in the last eight years.

It’s often just above 5%.

Latino leaders know that turnout is an issue. After Latino turnout plummeted statewide last November, Diana Robinson, political director for Make the Road Action PA, told The Inquirer that turnout becomes a vicious cycle: Candidates don’t campaign in Latino neighborhoods because of low turnout, and people don’t turn out because they don’t feel motivated.

“They are a group of voters that need to be persuaded” to vote, Robinson said last year.

Political preferences here are diffuse too, which further dilutes influence: With an already-small group fracturing its votes, it’s almost never had a deciding influence on an election.

Even when these voters are relatively united, they sometimes back losing candidates, such as during Carlos Vega’s 2021 run for district attorney. Or they support a campaign that wins so overwhelmingly, such as Clinton’s 2016 bid for president, that this group’s united votes don’t make the difference.

This cluster is the third-smallest in terms of registered Democrats, but it’s the second fastest growing. Young, upwardly mobile, well-educated voters in booming neighborhoods like Fishtown and Passyunk Square are the heart of this group, and they are often highly engaged.

They’re still not quite as likely to vote as the wealthy white liberal cluster, and they haven’t grown as quickly. But this group is bigger: It constitutes 15% of the city’s Democrats, and that figure is still rising.

In the 2015 mayoral primary, these voters accounted for 14% of the city’s vote. By the 2019 mayoral primary, they’d grown to 18%, and in the 2022 U.S. Senate primary, they accounted for 21%.

This group has consistently supported candidates on the left and is increasingly united. Bernie Sanders in 2016 and Larry Krasner in 2017 received their highest margins here, as did Fetterman in his 2016 and 2022 runs for U.S. Senate and his 2018 bid for lieutenant governor.

This moderately sized cluster is anchored by the vaunted Northwest coalition of Black leaders who worked for decades to organize these voters and advocate for their interests.

“The working-class Black voters in the Northwest are among the most coveted for a reason,” said Corrigan. “It’s because they turn out. That’s why every election cycle you see people courting the support, still, of leaders up there. They’re a big deal.”

» READ MORE: Philly’s Northwest Coalition has elected mayors. Will it determine the next one?

This group shows up regularly and tends to vote in a unified way, giving these voters considerable influence. They constitute 16% of the city’s active Democrats but regularly deliver around 18% of the total Democratic primary vote. That’s especially remarkable considering the cluster’s relatively low incomes and levels of education, which are typically associated with lower turnout.

In recent years, this group’s unity of voice has translated to higher-than-average margins for candidates who are generally the choice of the Democratic establishment. That includes Shapiro, Clinton, and McGinty in 2016, and also Krasner in his 2021 reelection bid.

When this group does diverge from the establishment, it’s often to support Black candidates. This group backed Philly native Malcolm Kenyatta in the 2022 U.S. Senate primary — and establishment favorite Conor Lamb got the second-most votes.

For sheer number of votes, white working-class moderates should be an important bloc. This cluster remains home to the second-largest group of registered Democrats. But as the city has grown and diversified, other voters’ interests have crowded out these old-school Democrats.

And turnout here has been unreliable.

The last time this group’s favored candidate prevailed citywide was in 2015, when it supplied one-fifth of the Democratic vote and boosted Kenney in his first mayoral bid by the city’s widest margins. Kenney, a native son of South Philly, hails from neighborhoods in this cluster.

Nonetheless, Kenney would have won that year without this group’s support. And as he embraced more progressive policies, this group cooled toward him in 2019, swinging from giving him his biggest margins four years earlier to his smallest.

In fact, this group tends to be most enthusiastic and unified when its votes are at odds with the rest of the city. For example, this group was the only one to offer substantive support to at-large City Council candidates Ed Neilson and Frank Rizzo Jr. in 2015, who did poorly elsewhere.

Likewise, this group’s vote share peaked in 2021 when it came out united against Krasner — who still won reelection easily.

Campaigns that manage to earn this group’s votes without alienating the rest of the city could tap a powerful vein of support.

“It’s nice to see someone knows we’re here,” said Paul Kaplan, a committeeman in the Northeast, at a recent rally for former Councilmember Allan Domb. The neighborhood is covered in signs for Domb, grocer Jeff Brown, and former Councilmember Cherelle Parker.

The largest group of registered Democrats is the cluster of less politically affiliated Black voters. Together they make up 29% of the city’s Democrats — almost one-third of the total. But their influence fluctuates: Participation varies a lot compared with other groups, and votes are often fractured across multiple candidates.

Still, this group’s size can give it formidable influence.

This group backed Krasner by the largest margin in the 2021 primary, and it has also tended to particularly support Black candidates.

In 2019, this group proved decisive in electing Katherine Gilmore Richardson to an at-large seat on Council. And in the 2022 U.S. Senate primary, half of this cluster’s votes went to Kenyatta, his strongest showing across the city.

That was nearly good enough for Kenyatta to win Philadelphia outright, though he came in third statewide.