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Warren wrote in the letter, which was mailed last week and posted on her website, that she has concerns about how President Donald Trump created DOGE and concerns about the DOGE proposals announced so far.

"But, your broad point — that the federal government spends trillions of dollars on wasteful spending is correct," Warren said.

Warren named UnitedHealth, and only UnitedHealth, in a section with the subtitle "Break up health care conglomerates and keep private equity out of the health care industry."

She suggested that vertical integration in health care, or situations in which health insurers like UnitedHealth also own pharmacy benefit managers, pharmacies and physician group practices, reduce competition and drive up costs for all payers, including federal health programs.

"Over the past four years, antitrust regulators have made significant strides to promote competition in the health care industry, including by suing the three largest PBMs, launching an antitrust investigation into UnitedHealth Group, the nation’s largest insurer and employer of physicians; and finalizing a rule banning noncompete provisions in contracts," Warren wrote.

Prominent Republicans have supported vigorous antitrust enforcement in health care, Warren said.

"DOGE should encourage antitrust agencies to promote competition in the health care industry, including by continuing the Department of Justice’s case against UnitedHealth Group, to lower health care costs for the federal government," Warren said.

Warren did not predict how much breaking up UnitedHealth or other big health care companies would affect federal health care spending.

Other Warren health care cost-cutting ideas: Warren said private equity investor funding for health care deals is another force pushing up health care prices.

"One study, for example, found that charges per patient were 50% higher after private equity invested in a practice," Warren said, without providing an estimate of the value of the impact on federal health care spending.

Warren suggested that changing how the government pays the insurers and managed care companies in the Medicare Advantage program could save more than $83 billion per year.

She said prescription drug market changes coud save federal health programs billions of dollars per year. She recommended making it more difficult for drug manufacturers to keep drugs patented and having the government exercise "march in" rights.

March-in rights regulations may let the government produce drugs itself when manufacturers set very high prices on new drugs based on federally funded medical research.