Vivek Ramaswamy, the Republican presidential candidate whose strident and sometimes unrealistic proposals have helped him stand out in the crowded primary field, said in a policy speech on Wednesday that he would fire more than 75 percent of the federal work force and shutter several major agencies.
Among the government organizations that Mr. Ramaswamy vowed to disband are the Department of Education, the F.B.I., the Food and Nutrition Service, the Nuclear Regulatory Commission and the Bureau of Alcohol, Tobacco, Firearms and Explosives. He said he would move some of their functions to other agencies and departments.
Mr. Ramaswamy, 38, also claimed he could make the changes unilaterally if he were to be elected president, putting forward a sweeping theory that the executive wields the power to restructure the federal government on his own and does not need to submit such proposals to Congress for approval.
His pitch was another echo of former President Donald J. Trump, whom he has modeled himself after and who sought to expand political control over the federal work force near the end of his term. Like Mr. Trump, Mr. Ramaswamy has also attacked parts of the federal government as a “deep state.”
“We will use executive authority to shut down the deep state,” Mr. Ramaswamy said on Wednesday at the America First Policy Institute in Washington, D.C. He flipped through posters displaying government organizational charts as well as what he claimed were common “myths” about the limitations of presidential authority.
But legal experts on the separation of powers and administrative law said the legal theories behind his proposal — detailed in an accompanying campaign white paper — were wrong and would not stand up to a court challenge.
Peter M. Shane, a scholar in residence at New York University and a specialist in separation-of-powers law, said the paper was “fantastical.” Peter L. Strauss, professor emeritus of law at Columbia University, said it took bits of statutory law “out of context” while “totally ignoring the Constitution,” which mandates that the U.S. Congress create the government departments and agencies that the president then supervises.
Mr. Ramaswamy’s vow to shutter large parts of the government and fire most of its workers would also unravel significant parts of the civil service and disrupt government services that are central to the operation of modern American society, including law enforcement, background checks for firearm purchases, student financial aid and special education programs.
About 2.25 million people work for the federal government in civilian roles. Cutting more than 75 percent of that work force would result in more than 1.6 million people being fired, saving billions of dollars in the federal budget but also shutting down critical functions of the government.
Mr. Ramaswamy did not make clear where all those eliminated jobs could come from.
The Congressional Budget Office has said that nearly 60 percent of federal civilian workers are in the Departments of Defense, Veterans Affairs, and Homeland Security — but Mr. Ramaswamy did not mention cuts for any of them in his remarks on Wednesday or in additional materials from his campaign discussing the proposals.
And while Mr. Ramaswamy named several agencies he said he would abolish, he added that he would move many of their functions to other organizations — suggesting that many of the same jobs would still exist elsewhere.
Mr. Ramaswamy also said he would abolish the Federal Bureau of Investigation, which became a frequent target of Trump-style Republicans after it investigated ties between Russia and Mr. Trump’s 2016 campaign.
Mr. Ramaswamy, who has less than 10 percent support in primary polls, has pitched himself as the future of the Republican Party — a radical conservative in the image of Mr. Trump.
His proposals on Wednesday reinforced the similarities between the former president and the political newcomer. They have both previously attacked specific agencies like the F.B.I. and large swaths of the civil service. Mr. Trump had also planned in a hypothetical second term to strip employment protections from tens of thousands of career civil servants, bring independent agencies under direct presidential control and purge officials he has vilified as “the sick political class that hates our country.”
But Mr. Ramaswamy’s proposals went even further, envisioning a wholesale dismantling. He took a moment during his speech to revel in the incendiary nature of his proposals.
“We’re going to get a lot of pushback to this speech,” he said. “I have no doubt about it.”