A coalition of voting rights advocates are criticizing the Obama administration for what they consider its failure to adhere to its own voter registration law. In a letter sent to the administration Wednesday, the groups said officials have not offered registration services through the federal healthcare exchanges set up under the Affordable Care Act, as the federal law requires it to do, Talking Points Memo reported.

Healthcare.gov, the website of the healthcare reform law known as Obamacare, does not ask people using the service if they would like to register to vote, said the coalition, which suggested it would take legal action. The National Voter Registration Act, the so-called Motor Voter law of 1993 law that expanded registration methods, requires that people seeking state services such driver’s licenses and ID cards, disability assistance, food stamps or Medicare get the opportunity to register to vote during the application process.

"We hope to avoid litigation, but we note that the NVRA includes a private right of action," stated the letter signed by Demos, ProjectVote and League of Women Voters. Separately, the groups have successfully sued states for not offering voter registration through public service programs, according to Talking Points Memo.

The coalition claimed in the letter that voter registration has gone down in some states where the federal government had to set up Medicaid enrollment websites. The number of people registered to vote since the Affordable Care Act took effect dropped from almost 12,000 registrations per month to approximately 10,000 per month, the letter stated.

“Overall, more than 3 million people have enrolled in Medicaid using healthcare.gov, and none of these individuals has been offered the voter registration services that federal law requires,” the coalition claimed. The voting rights advocates said they had been “extremely patient” and understanding, while the healthcare law was challenged before the U.S. Supreme Court. In June, the court ruled in King v. Burwell that the federal healthcare exchanges were constitutional.

“There is no longer any good reason for not improving the voter registration services provided through the [federal exchanges]," the letter stated.