Parents of children with special needs are speaking out as Senate Republicans return to Washington this week with an eye toward repealing and replacing Obamacare.

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Children from low-income families would be disproportionately affected by proposed cuts to Medicaid, a federal health care program that offers cheaper insurance options for mostly low-income Americans. But experts are warning that the Senate health care bill could be especially devastating for families with children who suffer from complex medical conditions, such as autism or Down syndrome.

There are about 11 million children with special health needs in the United States, including an estimated 5 to 6 million who are currently covered by Medicaid. Under the Senate bill, only 1.2 million of those children would be eligible for Supplemental Security Income (SSI) to help cover the extra costs of their health care needs.

The bill's narrow definition of "blind or disabled" would exclude millions from additional coverage, according to a recent report from the Kaiser Family Foundation. 

"They must come from impoverished families who can prove they are blind or have 'marked and severe functional limitations' that are fatal or will last continuously for at least a year," the group noted in an editorial for The Washington Post. "Under the bill, the federal government would continue to pay for a portion of their medical bills without setting any financial ceiling."

That standard would still leave millions of special needs children with inadequate coverage when Medicaid rollbacks take effect in 2021. . 

Families who lose out on that coverage could see medical bills skyrocket due to the high costs of caring for a special needs child. Medicaid is used to cover therapy, medical specialists, caretakers at home and school, emergency hospitalizations, medications, and various other special health care expenses.

Those bills add up. For example, the average cost of caring for an autistic child over their lifetime is $2.3 million, according to the advocacy group Autism Speaks.

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In response to the Republican health care plan, attorneys have started telling parents of special needs kids to make sure their finances are in order and to utilize third-party special needs trusts to "ensure they allot more money toward the care of their disabled children," CNBC reported.

"More than likely, parents of children with special needs may come to the conclusion that they can't rely on benefits, and they will have to be proactive," Russell Fishkind, an estate planning attorney, told CNBC. "We've seen a tremendous shift from the Obama administration to the Trump administration in goals and objectives for providing health-care plans."

"You need to take matters into your own hands," he said.