“Without access to the ACA's health and financial benefits, morelow- and middle-income people would face higher financial burdensand less access to necessary medical care,” says one analyst.(Photo: Diego M. Radzinschi/ALM)

The consequences of repealing the Affordable Care Act would bedire, warns a new study from the Urban Institute, aliberal-leaning think-tank.

The study comes in light of a lawsuit, brought by a number ofstates, that seeks to overturn the law in court. The suit, Texas v.U.S., argues that the repeal of the individual mandate as part ofthe 2017 tax bill invalidated the rest of the ACA.

In December U.S. District Judge Reed O'Connor agreed with theplaintiffs and ruled that the ACA is unconstitutional. However,O'Connor immediately granted a stay, allowing the law to remain ineffect while the ruling was appealed. The case is currently beingconsidered by the U.S. Court of Appeals for the 5th Circuit.

Related: What would health care be like in a post-ACAworld?

Scrapping the landmark law would result in 20 million peoplelosing health care coverage and the uninsured rate among thoseunder 65 would climb from 11 percent to 18 percent. Just over 50million people nationally would lack insurance.

The impact would be greatest among the 34 states that haveexpanded Medicaid to those up to 138 percent of the federal povertyline. The uninsured population would nearly double in those states.In states that have still not expanded Medicaid, the uninsuredpopulation would grow by 34 percent.

In other words, things would largely revert to the pre-ACAreality.

“Eliminating the ACA would be a major step backward for themillions of people who gained affordable healthcare coverage thisdecade,” said John Holahan, Institute Fellow at the UrbanInstitute. “Without access to the ACA's health and financialbenefits, more low- and middle-income people would face higherfinancial burdens and less access to necessary medical care.”

During the two years when they controlled both chambers ofCongress, Republicans could not agree on a way to repeal the ACA. Challenging the party'snine-year-old promise to repeal is the fact that the law has becomeincreasingly popular. Polls now consistently show majority supportfor keeping it in place.

The Trump administration is supporting the lawsuit, and haswritten a brief in support of the O'Connor's ruling. Meanwhile, theDemocratic-controlled House of Representatives has signed on todefend the law.

Read more: 

• The dismantling of the ACA: An (updated)timeline
• What to expect from the ACA in2019
• ACA marketplace holding steady, despiteturmoil