By AMANDA SEITZ

WASHINGTON (AP) — Secretary Robert F. Kennedy Jr. offered no new details Wednesday about his massive restructuring of the U.S. Department of Health and Human Services, the day after thousands of layoffs ricocheted through its agencies, hollowing out entire offices around the country in some cases.

Kennedy’s silence is prompting questions from Republican and Democratic lawmakers alike, with a bipartisan request for President Donald Trump’s health secretary to appear before a Senate committee next week to explain the cuts.

As many as 10,000 notices were sent to scientists, senior leaders, doctors, inspectors and others across the department in an effort to cut a quarter of its workforce. The agency itself has offered no specifics on which jobs have been eliminated, with the information instead coming largely from employees who have been dismissed.

“This overhaul is about realigning HHS with its core mission: to stop the chronic disease epidemic and Make America Healthy Again,” Kennedy said on social media, in his only comments addressing the layoffs so far. “It’s a win-win for taxpayers, and for every American we serve.”

The move, the department has said, is expected to save $1.8 billion from the agency’s $1.7 trillion annual budget — about one-tenth of 1%.

The department has not released final numbers but last week said it planned to eliminate 3,500 jobs from the Food and Drug Administration, 2,400 jobs at the Centers for Disease Control and Prevention, and 1,200 from the National Institutes of Health. Public health experts and top Democrats have raised alarms about how the deep cuts — about 25% of the department — will affect food and prescription drug safety, medical research and infectious disease prevention.

Still unclear is why certain jobs were eliminated and others were spared.

As the cuts were underway on Tuesday, Louisiana Sen. Bill Cassidy, a Republican, and Vermont Sen. Bernie Sanders, an independent who caucuses with Democrats, sent a letter to Kennedy calling him before the Senate’s health committee. In a statement, Cassidy said Kennedy’s appearance is part of his promise to appear quarterly before the committee.

“This will be a good opportunity for him to set the record straight and speak to the goals, structure and benefits of the proposed reorganization,” Cassidy’s statement said.

Rep. Diana Harshbarger, a Republican from Tennessee, said the House’s health subcommittee also has questions about job cuts.

“We’re going to find out what the layoffs were all about — 10,000 — we didn’t know it,” Harshbarger said Wednesday at a health care forum hosted by Politico. “We’re going to find out what the premise was for those layoffs.”

At the same event, special government employee Calley Means, a close adviser to Kennedy who is working at the White House, defended the cuts. He struggled, however, to offer an explanation on how the overhaul will improve Americans’ health. Some of his claims were met with shouts and hisses.

“The system is really on the wrong track,” Means said, later adding that he wants to see more research from the NIH.

Politico’s Dasha Burns pressed Means on how the NIH would conduct more research with fewer employees at the agency, which had fired more than 1,000 NIH scientists and other staff before this week’s layoffs. Trump’s Republican administration has yanked hundreds of NIH grants and delayed hundreds of millions of dollars in continuing or new research funds including for studies of cancer and to keep Alzheimer’s centers around the country running.

Means responded by asking: “Has NIH funding been slashed?”

This story has been corrected to show the savings is about one-tenth of 1%, not about 1%.

Associated Press writer Lauran Neergaard in Washington contributed.