(Bloomberg) -- Two top progressive Democrats asked antitrust regulators to examine UnitedHealth Group Inc.’s planned $3.3 billion purchase of home-health provider Amedisys Inc. and challenge deals that bring medical providers under the same ownership as health insurers.

The Department of Justice opened an in-depth probe into the deal in August, and the letter from Senator Elizabeth Warren and Representative Pramila Jayapal renews attention on the investigation. The lawmakers stopped short of telling regulators to block the deal, but Warren and Jayapal, who are leading voices on the left wing of the Democratic party, continue to pressure a Biden administration that has struggled to sway courts to block deals. 

UnitedHealth has combined insurance with doctors’ practices, drug benefits and other businesses to create the largest US health services company by revenue. It’s a playbook that rivals are trying to replicate, with companies such as CVS Health Corp. and Humana Inc. buying medical providers and expanding beyond insurance into many aspects of caring for patients directly.

Warren and Jayapal urged President Joe Biden’s antitrust watchdogs to “to closely scrutinize” the deal and “oppose the growing trend of insurers buying up health care providers to reduce competition,” in a letter Tuesday.

A Justice Department spokeswoman confirmed the agency received the letter and declined further comment. UnitedHealth had no comment Tuesday evening. An Amedisys representative didn’t respond.

The Amedisys transaction is the third UnitedHealth deal that federal antitrust enforcers have investigated over potential competition concerns.

Last year, the Justice Department challenged UnitedHealth’s bid to acquire health data and payments firm Change Healthcare Inc. A federal court sided with the companies following a trial, allowing the deal to close last year. The Federal Trade Commission — which shares jurisdiction with the Justice Department over antitrust — earlier this year probed UnitedHealth’s deal to acquire home-health company LHC Group. The companies closed the merger in February after the FTC said it wouldn’t challenge the deal.

Analysts expect the Justice Department’s probe to focus on potential overlaps between LHC Group, which has about 30,000 employees who provide more than 12 million annual in-home patient-focused interventions, and Amedisys. The combination of LHC Group and Amedisys would give it about 10% of the national home health market, according to investment firm William Blair, more than what’s controlled by the current largest players, Humana CenterWell Home Health, formerly Kindred at Home. 

Thousands of companies provide in-home care and none has 10% of the market, UnitedHealth said when the purchase was announced in June. That level of competition made the company “confident it can secure approval for the combination,” UnitedHealth said at the time.

Warren and Jayapal argued that UnitedHealth has accumulated market power because of “lax antitrust enforcement” and acquisitions of doctor groups that are too small to trigger antitrust reviews. They also said the agencies should have blocked UnitedHealth’s acquisition of LHC Group.

Warren has played a key role in the Biden administration’s antitrust efforts, maintaining close ties with the leaders at the FTC and Justice Department’s antitrust division, and has written more than a dozen letters to them urging action on particular deals. Since 2021, the FTC or DOJ has initiated in-depth probes in nearly every merger she has called out and sought to block five them. 

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