(CNN) Two Democratic members of Florida's congressional delegation have asked the federal government to step in and help after the state's removal of thousands of children from a Florida Medicaid program.

"We have seen over the years that the State of Florida has evaded its legal responsibilities in many instances to ensure access to care for the children of Florida," Sen. Bill Nelson and Rep. Kathy Castor wrote in a letter to Health and Human Services Secretary Tom Price on Tuesday.

The letter comes in the wake of a CNN story detailing how Florida's Republican administration took 13,074 children off a Medicaid insurance plan called Children's Medical Services and put them on privately managed Medicaid plans in 2015.

For more than 40 years, Children's Medical Services, or CMS, has specialized in caring for Florida children on Medicaid with special medical needs. The children who were removed and put on other Medicaid plans had health problems such as birth defects, heart disease, diabetes and blindness. Their new plans did not specialize in caring for children with these types of medical conditions.

Castor told CNN on Wednesday that the state of Florida "clearly" did something wrong when it moved the children from CMS to the privately managed Medicaid plans.

"Florida had one of the highest-quality and most efficient treatment and care programs for children with special health care needs," she said. "They've obliterated that."

"We urge HHS to exercise its oversight and enforcement authority to ensure that children in Florida are appropriately enrolled in the plan that best fits their needs," Nelson and Castor wrote in their letter.

Mara Gambineri, a spokeswoman for the Florida Department of Health, said Tuesday that the department is "100 percent focused on making sure the programs we manage are providing quality care -- especially to children."

"Any assertion that children have been denied care or are not receiving services is absolutely false," she added.

In September 2015, a state administrative law judge ruled that the Department of Health had unlawfully removed the children from CMS and ordered it to stop.

The state stopped using the screening method in question, but it wasn't until last month that the department wrote letters to families letting them know their children could be rescreened to be put back on CMS.

The lawmakers questioned why the letters went to only 6,081 parents when more than 13,000 children were kicked out of CMS.

"It remains unclear why the state chose to contact only half of the families affected, what criteria the state used in making the determination of which families to contact, and how many children are actually reenrolled after being revaluated," Nelson and Castor wrote.

"It's unconscionable. There is no reasonable explanation for the state of Florida to be dragging their feet on this," Castor said.

"The state of Florida and DOH have not followed through with their responsibilities as directed by the courts," she said. "They've left these children in the lurch. They've said they're going to take care of it, and they've utterly failed to do that."

Gambineri said in early August that the letters went to parents of children who were removed from CMS and put on another Medicaid plan and were still on that plan and financially eligible for Medicaid.

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Dr. Louis St. Petery, former executive vice president of the Florida chapter of the American Academy of Pediatrics, said he doesn't trust the state to reach out to all of the affected families.

He pointed out that the state didn't reach out to the families soon after the judge's decision, even though he urged officials to do so.

"There's been a lack of transparency all the way through, which CNN tracked down," he said. "I always felt that for the Department of Health, the end justified the means, and the end was to get these kids off of CMS."

St. Petery and some other pediatricians think the state switched the children to Medicaid plans run by private insurance companies because most of those companies have been generous donors to Florida Republican Party committees.

A statement by the Department of Health called this allegation "100 percent false."