Harvard Researchers Say Strong Campaigns, Effective Anti-Trump Messaging Boosted Democrats in 2025 Elections

Political scientists at Harvard said Democratic victories in last week’s off-cycle elections were a sign of powerful backlash to Donald Trump’s presidency, but that Democrats could not afford to rest on their laurels ahead of the 2026 midterms.

Tuesday’s results were a rare ray of light for a party that has been out of power and frequently adrift since it lost the presidency and both houses of Congress in 2024 — though none of the highest-profile Democratic victories took place in swing states.

Rep. Mikie Sherrill (D-N.J.) secured the New Jersey governorship last week, and former Rep. Abigail Spanberger (D-Va.) flipped the Virginia governor’s office to the Democrats. New York state legislator Zohran Mamdani won the New York City mayoralty as a self-described democratic socialist. And Proposition 50 — a ballot measure allowing California to redraw congressional districts in favor of Democrats — signaled that voters in the solidly blue state were eager to clap back against Republican states’ redistricting.

Government professor Steven R. Levitsky said last Tuesday’s results showed that opposition to Trump was powerful enough to carry the day for Democrats.

“Especially in midterm elections, the Democratic Party doesn’t really need a strategy to win,” Levitsky said. “Being anti-Trump was enough.”

Liz McKenna, an assistant professor of public policy at HKS who researches how democracy is sustained, wrote in an email to The Crimson that Democrats not only performed well — an expected result for the out-of-power party — but won with margins that exceeded predictions.

“That said, Democrats also performed well in recent midterms and off-cycle elections but still lost significant ground in 2024, so they should take nothing for granted,” she wrote.

Tuesday’s elections added new fuel to debates over whether Democrats could best strengthen their coalition by shifting to the center or embracing their party’s left wing. Moderates Sherrill and Spanberger wielded their congressional experience and military and intelligence backgrounds to win governor’s seats. But Mamdani secured the New York City mayor’s office after running an unapologetically progressive campaign.

Government and Sociology professor Theda R. Skocpol said the results last week showed that Democrats were able to lodge criticisms of the Trump administration that held wide appeal to voters, even among very different constituencies.

“The Democratic Party managed to find some broad critiques of the MAGA and Trump Republican ascendancy that could be spelled out in interesting and robust ways in different places, in different ways,” Skocpol said. “This was a repudiation of Trump and Trumpism.”

Levitsky said the results reinforced that Democrats must field candidates across multiple wings of the party, rather than trying to unite a heterogeneous coalition behind a single ideological line.

“I want to put my head in the toilet when I hear these debates between ‘oh, the party should go left, or the party should go center,’” he said. “The party clearly has to do both of those things in different places to win at the national level.”

Some Harvard faculty said Sherrill, Spanberger, and Mamdani likely succeeded by running on platforms that emphasized voters’ day-to-day concerns and maintaining strong ground games.

Harvard Kennedy School professor Stephen Goldsmith, who previously served as deputy mayor of New York City and mayor of Indianapolis, said candidates’ focus on quality of life issues made “a really big difference.”

“People care about those issues,” Goldsmith said. “City and state residents expect from their governors and mayors pragmatic execution of the basic foundation of government. All three of these — Virginia, New Jersey and New York — were individuals who were committed to improving the quality of life.”

Harvard Kennedy School lecturer Marshall L. Ganz ’64 — who advised Mamdani’s campaign — said the mayor-elect won in part by effectively mobilizing tens of thousands of volunteers and convincing voters that he cared about the issues that mattered to them.

“He actually had conversations with people. Candidates mostly don’t do that,” Ganz said. “He wasn’t pitching. He was listening. People don’t do that.”

Ganz, who met with Trump and Harris campaign leadership immediately after the 2024 election, said he recalled that the Harris campaign “had been trying to tell people how they ought to feel, rather than listening to how they felt.” Mamdani, Ganz said, succeeded by taking a less prescriptive approach.

McKenna wrote that the Mamdani campaign was particularly effective at mobilizing membership-based groups to win back constituencies that had swung to the right in the 2024 elections.

She pointed to an exit poll by the Asian American Legal Defense and Education Fund and the Asian American Federation that suggested 20 percent of Mamdani’s voters had backed Trump in 2024.

Levitsky said last week’s elections were the strongest sign so far that Democrats were able to rebound from their across-the-board loss to Trump and his party in 2024.

“This was the first time that the opposition to Trumpist authoritarianism landed a punch back,” Levitsky said. “We don’t know what that’ll mean in the longer term, whether this is a turning point or not, but this was the first time that the opposition really landed a blow in 10 months.”

Skocpol said that Democrats should see Sherrill’s victory — by more than 13 points over Republican candidate, former state legislator Giacchino Michael “Jack” Ciattarelli — as a particularly heartening sign. The results showed Sherrill was able to pull off a decisive win despite the unpopularity of her predecessor, Gov. Phil Murphy, a Democrat, Skocpol said.

Democrats are also operating without one potential structural challenge in the 2026 midterms, Skocpol said. Because there is no presidential race until 2028, the party can opt for a big-tent strategy without needing to unite behind a single presidential candidate.

But Skocpol cautioned that Democrats may have little margin for error in the next election cycle, where a loss could allow Trump and the Republican Party to further consolidate their power.

“They have to win in 2026,” she said. “It’s probably one of the most decisive elections. They have to take at least one house of the Congress.”