WASHINGTON — The White House on Thursday proposed a radical overhaul of the federal government that, if implemented, would transform the swath of agencies that manage Americans' food, public education, social services and even air travel.

Other presidents have met mixed success in their attempts to streamline government functions, but Trump administration officials said they intend to shake up what one called a "nonsensical" bureaucracy that requires multiple agencies - from the Food and Drug Administration to the Department of Agriculture - to regulate the production and distribution of a roast beef sandwich.

"We're dealing with a government that's so byzantine you don't know where to start," Mick Mulvaney, director of the Office of Management and Budget, told President Donald Trump's Cabinet as he unveiled the results of a 14-month effort he called one of the "biggest pieces so far of our plan to drain the swamp." As an example, Mulvaney said 45 job training programs scattered across government would be consolidated into 16.

But the 132-page plan, which creates some offices and collapses others, is silent on a critical question for federal workers and the unions representing them: How many jobs would be lost under the White House proposals? Skeptical employee union leaders promptly accused the White House of gutting programs to turn federal jobs over to the private sector.

Many key recommendations - chief among them merging the Education and Labor departments and shifting food programs for low-income Americans to the Department of Health and Human Services - would require approval from Congress, where Democrats immediately assailed them as dead on arrival.

Rep. Gerald Connolly, D, whose northern Virginia district includes thousands of federal workers, accused the administration of reorganizing agencies that administer safety-net programs as a guise for cutting them. "Don't fall for this," he said in a statement.

But Sen. Ron Johnson, R-Wis., chairman of the Senate committee that will first consider the biggest proposals, praised the reorganization as "thinking big and 'outside the box' to bring effective reform and reorganization to a government structure developed for the previous century."

"The vast majority of people I ask believe the federal government is badly broken," Johnson said in a statement.

Some of the proposals have been tried before and were derailed by intense political opposition. In 2012, President Barack Obama proposed shifting the National Oceanographic and Atmospheric Administration to the Interior Department, an effort that went nowhere. The Trump plan envisions a more modest shift, moving a small division of the National Oceanic and Atmospheric Administration, the National Marine Fisheries Service, to Interior.

Other, less dramatic changes - such as shifting responsibility for employee background checks from a downsized Office of Personnel Management to the Defense Department - could be achieved through the budget process without going through Congress, administration officials said.

"We all know that government needs to change," OMB Deputy Director for Management Margaret Weichert said during a news briefing. She called the proposal the start of a "national dialogue" in an acknowledgment that the White House cannot make many of the changes on its own.

Weichert acknowledged that the administration deliberately did not consult with members of Congress as it solicited ideas from agency leaders and heard from 100,000 ordinary Americans who sent suggestions to the White House.

"We didn't want to lose good proposals and have them die on the vine if we went public too soon," Weichert said, calling congressional committees "part of that legacy infrastructure" that has often resisted big changes.

The proposal's centerpieces and most controversial elements are the Labor and Education merger into a new Department of Education and the Workforce, and a reconstituted Department of Health and Human Services, which would be renamed the Department of Health and Public Welfare.

Weichert said a rebranded Health and Human Services agency would "better capture the nature of its programs." Asked about reviving the use of "welfare'' in the agency title - a term that many liberals view as pejorative - Weichert bristled. "It's business as usual in Washington to politicize things," she said.

Democratic National Committee Chairman and former labor secretary Tom Perez called the idea of dismantling the Labor Department an assault not just on U.S. workers but on agency employees.

"The Department of Labor provides critical services to protect working conditions, help retirees and ensure that every worker is paid a fair wage for their hard work," Perez said.

Other plan elements likely to draw opposition are familiar calls to privatize some government functions, including air traffic control and the U.S. Postal Service, which is struggling financially in the Internet age.

The plan also proposes giving Cabinet secretaries new security details made up of U.S. marshals to "professionalize and standardize" protective work.

The administration ran into criticism by providing such a detail to Education Secretary Betsy DeVos, deploying more than a dozen people to protect her at an estimated cost of millions of dollars. Such details are typically more robust and expensive than the standard internal security provided by non-law enforcement agencies.

Other proposals are less controversial, but if history is a guide, they still may run into obstacles.

The plan proposes creating a single food safety agency under the Agriculture Department, shrinking the Food and Drug Administration's role in regulating parts of the food industry. Housing programs now run from Agriculture would shift to Housing and Urban Development. Some Army Corps of Engineers functions would move to the Transportation and Interior departments.

Privatizing more than 30,000 FAA workers has been tried twice since the GOP gained control on Capitol Hill, and both times it has failed to gain sufficient traction. The latest effort by House Transportation Committee Chairman Bill Shuster, R-Pa., would have revived an effort to place air traffic control for a costly new aviation system in a private nonprofit corporation. But the proposal has languished on the Hill.

The Trump plan also attempts to consolidate various energy and environmental prerogatives currently spread across government agencies.

The Environmental Protection Agency's Superfund program would absorb portions of hazardous site cleanup programs run by Interior and Agriculture.

And the Energy Department, which was threatened with severe cuts to its programs in back-to-back White House budget proposals, would combine several applied-energy programs into a single new office. The administration also floated having that department, along with the independent Tennessee Valley Authority, sell some federally controlled electricity transmission assets in the South and West to private operators.

Paul Bledsoe, a former Energy Department consultant under Obama, called the proposed reorganization for the Energy Department "a backdoor attempt to cut energy innovation funding" that Congress is likely to reject.

The Trump administration plan proposes to shift responsibility for harbor channels and inland waterways from the U.S. Army Corps of Engineers to the Department of Transportation - and, in some cases, out of federal control altogether.

If approved, that could affect major U.S. ports from New York to Los Angeles, and numerous locales between.

Beyond simply moving work from one government agency to another, the administration's blueprint suggests major federal waterways could be shifted to new ownership. It is unclear whether ownership might flow to states, localities or private firms, and a Transportation Department official provided no immediate clarification.

The American Federation of Government Employees, the largest union representing federal workers, promptly assailed the plan as a "scheme to gut federal services," in part by targeting domestic programs that have long been unpopular with conservatives.

"There's little reason to believe this reorganization plan is anything more than a scheme to eliminate essential programs and public-service jobs, reward or punish political appointees depending on their allegiance to the White House, and privatize government programs to reward political donors," AFGE President David Cox Sr. said in a statement.

AFGE and other unions already are at war with the White House over executive orders issued in May that dilute the unions' power to work on behalf of federal employees.

Weichert was adamant that "the objective of this exercise . . . was not to cut jobs." She noted that the federal workforce is aging, with 60 percent of its employees eligible to retire in the next 10 years. Meanwhile, she said, many corners of government - particularly in cybersecurity and other information technology specialties - need qualified workers.

She suggested that the administration wants to modernize the workforce through "retraining, reskilling and redeploying" employees.

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The Washington Post's Dino Grandoni, Ashley Halsey III, Michael Laris, Amy Goldstein, Devlin Barrett and Darryl Fears contributed to this report.