Health Secretary Robert F. Kennedy Jr. efforts to revamp America's food system have hit their biggest hurdle yet: The White House.

Two years ago, the Trump campaign joined forces with Kennedy, embracing his ambition to wage war on chronic disease. But concerns about whether his ideas on food are even feasible has prompted clashes within the administration, casting uncertainty over a once potent political agenda that drew support from millions of voters.

At a July meeting convened by senior White House officials, tensions were running high. Up for discussion was a definition of ultraprocessed food-a wonky but critical part of Kennedy's plans to overhaul the U.S. food supply-and whether it should undergo a layer of further review by White House staff.

The definition that health officials pushed for: Processed food should be considered ultraprocessed if it contains ingredients such as artificial colors, nonnutritive sweeteners or chemical preservatives, with key exemptions, according to people familiar with the matter and a document viewed by The Wall Street Journal. White House staffers were concerned that definition could cover the vast majority of food in U.S. grocery stores and support existing efforts to sue food companies over bad health outcomes.

One of Kennedy's top aides, Calley Means, accused White House officials of trying to block the definition to cater to special interests, some of the people said. Means, a fiery influencer and wellness author, raised his voice and repeatedly asked why the definition required further review, saying it wasn't open for further debate. He said Kennedy's health department had already worked on it for months and had vetted it with scientists.

In response, White House officials highlighted concerns that the definition could be exploited by the plaintiffs' bar and be grounds for a lawsuit against the government. They also pointed to its potential impact on the food industry and international trade agreements.

The internal discord has stalled three separate efforts to curb the country's reliance on ultraprocessed foods, a cornerstone of Kennedy's agenda to remake the U.S. food supply.

Means has mounted an expansive effort to roll out policies in Trump's second term, saying the administration needs to deliver for its "Make America Healthy Again" supporters. White House officials have often viewed him as overly aggressive, pushing policies that aren't feasible and unwilling to compromise to make them more achievable, officials said.

Means complained in other meetings that he believed some White House officials were behaving like it was their job to help food industry lobbyists work against Kennedy's agenda, one person said.

"The White House has repeatedly taken on special interests and broken processes to deliver effective and legally durable MAHA policies," said White House spokesman Kush Desai. "The entire Trump administration continues to work closely with stakeholders and industry leaders to continue overhauling our country's food and updating nutritional guidance."

White House chief of staff Susie Wiles had voiced support for Kennedy's agenda throughout the year and met with MAHA advocates in April to hear their concerns about the administration's support for pesticides and other issues. Health and Human Services didn't respond to requests for comment.

The outcome of the July meeting: White House officials decided that the ultraprocessed food definition would go through further review, people familiar with the decision said. Still, Kennedy's team believed they had clearance to unveil the definition, and planned a high-profile food policy event in August, some of the people said. Kennedy's allies were jubilant.

HHS' headquarters was decked out for the event with red, white and blue lighting and posters depicting artificial food dye as a monster. Officials and supporters had readied talking points to accompany the definition.

The weekend before the event, the White House reversed course, nixing a debut of the full definition. Certain White House officials were caught off guard, unaware the health department aimed to unveil it, a person familiar with the matter said.

Mark Paoletta, a White House lawyer who is running the office that reviews all new regulations, opposed the plan. Paoletta viewed the definition as adding new rules when the administration's goal is to cut red tape, people familiar with the matter said. He also agreed with industry arguments that the measure could be a boon to the trial bar, the people said.

Wiles stopped returning calls from MAHA advocates that weekend, people familiar with the matter said.

HHS officials still held the event, premiering a separate food effort, and saying they were continuing to work on the ultraprocessed food policy.

Means and Dr. Heidi Overton, Trump's nominee to lead the Food and Drug Administration, tried again to publish the definition at the end of the month, but were again forbidden by others in the White House, people familiar with the matter said.

In the weeks since the definition's scuttled unveiling, many food and agriculture groups and companies, as well as health groups and consumer advocates, have sought to weigh in. White House staff have met to discuss the definition with groups representing farmers, meatpackers, food and beverage manufacturers, grocers and more.

"We have the shortest lifespans of any wealthy country," said Jerold Mande, chief executive of Nourish Science, a nonprofit, and a former FDA and Agriculture Department official. "It's an urgent problem that the MAHA movement and RFK Jr. came to power saying they were going to address and they've had a decidedly mixed record."

Some food executives have said that they focus on a range of factors when evaluating their products.

"Categorizing a set of foods by the way they're processed I think is wrong headed, and also can lead to outcomes that are the opposite of maybe what some people have intended," said General Mills Chief Executive Jeff Harmening.

Other avenues

Kennedy's team tried to push for more aggressive food policy in other avenues. Earlier this year, USDA drafted a framework for a new rule governing school meals, which would cost school districts about $2 billion over five years. Means demanded stricter limits on added sugars, protein in breakfasts and 100% whole grain products, changes that roughly quadrupled the cost.

During one meeting of government officials about the rule, USDA staff said food manufacturers and schools should have more time to adapt to the changes Means proposed. Means grew visibly frustrated, saying a weaker rule would make the Trump administration look like it was "ok with poisoning kids."

His pressure appeared to work. USDA Secretary Brooke Rollins encouraged her department to work with Kennedy's team, people familiar with the matter said, and USDA ultimately deferred to HHS on much of the rule.

Some Trump administration officials even relayed a private message to industry and schools: speak up about the rule's problems once it is proposed, because we can't stop it internally, people familiar with the matter said.

Then the rule stalled at the White House.

In late August, Kennedy spoke at a USDA rally celebrating the country's child nutrition programs. He hoped to help showcase the rule but the White House prohibited this plan too, people familiar with the matter said. White House staffers including former USDA employee Anne DeCesaro worried the rule was unworkable for schools and have slowed its release, the people said.

A spokesman for USDA said the administration is working together to deliver healthier options in schools. "Whether school meals or ultraprocessed foods, these are major policy updates that require thorough review, conversation, and feedback," the spokesman said.

In addition to the two stalled policies, Kennedy has yet to launch a safety review of some of the most common ingredients in ultraprocessed food. Last year, former FDA commissioner David Kessler asked the agency to declare certain refined carbohydrates unsafe.

In March, Kennedy backed Kessler's effort, according to a draft letter reviewed by the Journal. "I believe your petition points toward a historic opportunity to significantly improve the quality of our food supply and thus the health of our citizens," he wrote. The text of the draft letter was first reported by the Washington Post.

The White House blocked release of the letter, people familiar with the matter said.