When President Joe Biden directed the Occupational Safety and Health Administration (OSHA) on Sept. 9 to impose strict COVID-19 vaccination and testing protocols on large businesses, the OSHA employees were ready. It marked the first time in nearly five years that the small agency had the opportunity to fulfill its mission to protect workers across industries from “recognized serious hazards.” But it also highlighted tensions between OSHA and the White House, exposing simmering resentments over how the White House has approached working with the Department of Labor during the pandemic, according to three former top OSHA officials.

“It’s been a very frustrating nine months for OSHA,” says Former Deputy Assistant Secretary of Labor for OSHA Jordan Barab, referencing a series of instructions from the Biden Administration, including the most recent plan for a vaccine and testing mandate. “This whole thing was basically thought up in the White House.”

The Emergency Temporary Standard (ETS) Biden directed OSHA to draft this month will require businesses with 100 or more employees to require COVID-19 vaccines or weekly testing among employees. The rule will cover more than 80 million workers in America, according to a Labor Department (DOL) spokesperson. But the scope of the rule was drafted in the White House without significant input from agency experts, former OSHA officials say—and they believe it could go farther.

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“OSHA staff and leaders and DOL staff and leaders would prefer a more comprehensive standard,” Barab says. “I think there is a lot of frustration that this is limited exclusively to just vaccinations or testing. The mitigation measures are totally absent.”

Current OSHA staff are not authorized to speak on the record about ongoing rule-making. The White House directed questions to DOL. When asked about the working relationship between OSHA and the White House, a spokesperson for DOL said, “The staff at OSHA are committed to the safety and health of America’s workforce and are working expeditiously on the ETS, which will provide protections for workers and support for employers throughout the country, using tools we know are safe and effective.”

The tension between the agency and the White House traces back to Biden’s second day in office, when he directed OSHA to create a comprehensive ETS that could prevent worker exposure to COVID-19. A team including health and safety specialists, industrial hygienists, engineers and attorneys collaborated to write a rule for all workplaces. The result was a 780-page unpublished ETS that included widespread mandates for masks, six feet of separation, proper ventilation, cleaning and disinfection, quarantining sick workers, and a notification system that would have told workers if they were exposed to the virus, according to the draft text of the rule. (It did not include vaccination requirements, as OSHA wrote the draft before vaccines were widely available.) The unpublished ETS is available due to a Freedom of Information Act request.

But the ETS that the President had personally requested “never saw the light of day,” says Debbie Berkowitz, a former OSHA official and National Employment Law Project (NELP) safety program director. “I think the Administration didn’t have the political will to get it done.”

One problem, experts say, is that the ETS was overtaken by vaccine availability, evolving Centers for Disease Control and Prevention (CDC) guidelines, and animosity toward federal mandates.

The Biden Administration had pushed the original release date for the first proposed standard from March 15 to June. In that time, an increasing number of people began receiving vaccines, leading the CDC to loosen its guidance. In March, the CDC announced that vaccinated individuals could have small indoor gatherings without masks, and a month later, the agency said that vaccinated individuals could go outside without masks. In May, the public health agency announced fully vaccinated people could stop wearing masks in most places—outdoors and inside.

As the CDC paved the way for restrictions to ease, the original argument for the measures in the ETS—that there was a “grave danger” to workers without actions like masking—appeared to weaken.

Public opinion may not have been behind the original ETS, either. Support for a widespread federal response is higher now than it was at the start of Biden’s term, says N’dea Moore-Petinak, a doctoral candidate at the University of Michigan and coauthor of the book Coronavirus Politics. And businesses may be more open to a vaccine and testing mandate than they would be to a masking mandate like the one included in the original ETS, says Glenn Cohen, an expert on health law and bioethics at Harvard Law School. “While I think masking is terrific, politically it’s a harder sell and the compliance rates may be lower,” he says. “With vaccination, it’s easier to ensure compliance.”

By June, only the portion of the ETS draft related to healthcare workplaces would go into effect.

The White House’s retreat from the original, comprehensive ETS disappointed OSHA staffers, according to the former OSHA officials. The agency, which had been the target of Trump’s ire, already felt hamstrung during the first year of the pandemic. “We got hit with a pandemic in March of 2020 and the Trump Administration [had] decimated OSHA,” Secretary of Labor Marty Walsh told TIME during an Ohio trip last month. The agency did few inspections in early 2020, and inspectors were not given the personal protective equipment needed to enter workplaces. Biden’s decision to spike the comprehensive ETS felt like they still couldn’t perform the job they were hired to do. “It was very frustrating for everyone at OSHA, from the acting administrator all the way down to the staff working every single weekend for months on the standard,” Barab says.

That this ETS applies only to businesses with 100 or more employees also marked a departure from the agency’s standards. Limiting the vaccination and testing rule to larger businesses has no precedence in past guidelines, says David Michaels, OSHA’s administrator from 2009 to 2017. “When it comes to protecting workers from serious hazards, OSHA doesn’t distinguish between workplaces of different sizes,” he says.

Now, although the current ETS lacks OSHA officials’ lengthy wish-list of protective measures from last spring, the small agency, which has limited ability to penalize non-compliance, is tasked with both writing and enforcing it. In the DOL budget request, the Biden Administration has asked for $664.6 million to fund the agency for FY 2022 starting Oct. 1; House Democrats requested $692 million. (Under Trump, the budget for OSHA was $100 million less, at just under $592 million.)

Still, most experts think the new ETS is better than nothing. “This is not perfect, it’s not going to work everywhere,” says Michaels. “It will certainly increase protections for workers in many workplaces and it will contribute to slowing down this pandemic. I’d like to see a stronger regulation, but this is a very good first step.”

-With reporting by Abby Vesoulis/Dayton, OH

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Write to Julia Zorthian at julia.zorthian@time.com.