UnitedHealth said Tuesday all of its new employer-sponsored plans in 2020 will pass discounts paid to so-called pharmacy benefits managers to consumers at the drug store counter.

The move builds on the existing discount programs that were announced a year ago that the company said will serve more than 9 million consumers this year. The insurer also said existing members would have the choice of adopting this plan during contract renewal.

"Patients are seeing concrete benefits from UnitedHealthcare's groundbreaking point-of-sale discount program, which is just one element in our aggressive drive to help deliver better health, lower costs and a better experience," UnitedHealthcare President Dan Schumacher said in a release.

UnitedHealth said its rebate program has lowered costs for consumers by $130 per prescription on average.

The Trump administration has proposed doing away with the rebate system for Medicare plans but has not gone as far as extending the ban to commercial plans. Drug manufacturers pay PBMs the rebates for getting their drugs covered by Medicare's Part D prescription plan.

One week ago, Sen. Mike Braun, R-Ind., introduced the Drug Price Transparency Act, which would ban rebates for commercial plans.

UnitedHealth's rivals, CVS Health's Caremark unit and Cigna's newly acquired Express Scripts unit, offered plans that passed discounts to consumers at the point of the sale for 2019.

The insurers have indicated that adoption of those plans has been slow for 2019, but investors see increased pressure for them to abandon rebates across all of their businesses for 2020 contracts, potentially pressuring margins.

--Reuters contributed to this report.