A new populist fever is coursing through the midterms, forcing campaigns to retreat and recalibrate as they confront a groundswell of hostility toward AI data centers.Why it matters: Grassroots pressure is breaking the bipartisan consensus that enabled America's AI buildout. Candidates in both parties are now racing to distance themselves from projects their own leaders spent years courting.The big picture: What started as scattered, localized NIMBYism is scaling into a national cross-partisan movement that could slow America's race for AI supremacy.In Ohio, former Democratic Sen. Sherrod Brown has spent millions on a summer ad campaign branding Republican Sen. Jon Husted as "the face of data centers," weaponizing Husted's years of courting the industry as lieutenant governor. With major projects already underway, the National Republican Senatorial Committee (NRSC) privately warned AI companies a Husted loss could chill support for data centers nationwide.In Texas, Republican Gov. Greg Abbott — who once declared Texas "the epicenter of AI development" — is now pushing to restrict data centers in rural communities and strip away tax incentives after Democrat Gina Hinojosa branded the state the "wild west of data centers."In Pennsylvania, Gov. Josh Shapiro — who spent years courting data-center investment — imposed sweeping new guardrails this week after Republican challenger Stacy Garrity accused him of "rolling out the red carpet" for developers.In Wisconsin, GOP gubernatorial nominee Tom Tiffany is running ads attacking his Democratic opponent as "data center David Crowley." That puts Tiffany, a close Trump ally, on the same side of the issue as Crowley's former primary rival, democratic socialist Francesca Hong.In Wyoming, Republican Chuck Gray won Tuesday's primary for the state's open House seat after running ads promising to "stop data centers" and calling for a federal ban.In Michigan, Democratic Senate nominee Abdul El-Sayed called for state and federal moratoriums on new data centers days before winning his primary.Behind the scenes: The backlash has caught the industry and political establishment flat-footed, triggering finger-pointing over who failed to see it coming — and who should pay to contain it.One Republican operative unloaded on GOP groups that have spent months raising money from tech companies while holding back resources that could help candidates weather the attacks."Maybe they should stop trying to shake down these tech companies and start putting the money that they raised from them into these elections," the operative said, pointing to the NRSC. "What are they waiting for?"New York Gov. Kathy Hochul — who last month imposed the nation's first statewide moratorium on new hyperscale data centers — blasted the NRSC's push for AI companies to improve their messaging as "tone deaf" and "wildly inappropriate.""I don't think it's government's role, certainly not the United States Senate's role, to be telling companies how to market their products," Hochul told Axios.The other side: The White House and AI companies know they have a serious political problem, and moved earlier this year to address the biggest grievances at their source.President Trump's ratepayer-protection pledge requires companies to cover the power generation and grid upgrades their projects require, rather than stick local customers with the bill.Google, Microsoft, Meta, Oracle, xAI, OpenAI and Amazon have all signed on, keenly aware of the threat to their massive AI ambitions.What they're saying: "The hyperscalers and the data center companies are on the defense. Their comms teams don't know how to fight," the Republican operative told Axios. "They're just used to fluffy ads and corporate media."Industry officials say the fight will be won locally, with companies expanding workforce programs, community funds and promises to cover the power, water and infrastructure they consume.The GOP operative said that given the existing ratepayer-protection pledge, the winning message is simple: "Not a single shovel should go into the ground if a data center is pulling resources from the community."The bottom line: Trump has made data centers central to his race for AI supremacy, arguing that communities should welcome the projects for their jobs, investment and strategic value.On Wednesday, he acknowledged the political problem himself, saying data centers "could use a little public relations help."But he went on to insist: "If I were a governor or a mayor, I would want that plant in my community."