Romney's plan would protect people with pre-existing conditions only if they maintain continuous healthcare coverage, not if they become uninsured. "I do have a plan that deals with people with pre-existing conditions," Romney said in the debate.
Wasserman Schultz called the statement an "empty, dishonest promise" in her fundraising email.
"As a breast cancer survivor and someone living with a pre-existing condition, this statement was more personally offensive than any of [Romney's] repeated promises to repeal Obamacare," wrote Wasserman Schultz.
"Obamacare protects us from unfair practices like lifetime caps on your coverage, denial of coverage because of pre-existing conditions, and being dropped from your policy exactly when you need it most. Mitt Romney will take that all away — but when he's asked point-blank about it, he won't admit it."
Romney's claim is "not only the worst kind of politics," Wasserman Schultz went on, "it's toying with real people's lives."
The Republican National Committee (RNC) said the DNC chief's attack "reeks of desperation."
"Debbie Wasserman Schultz’s false attack on Mitt Romney’s healthcare policy will not work and reeks of desperation by campaign that has no positive vision for the country and is resorting to negative attacks," said RNC spokesperson Kirsten Kukowski. "Mitt Romney’s position on protecting those with pre-existing conditions has been consistent and clear."
Kukowski pointed to a note from the Romney campaign's policy director, Lanhee Chen, saying Romney's proposal would protect those with pre-existing conditions who have maintained continuous coverage.
Chen also said that under Romney, states would have "the flexibility and resources to design programs" aimed at helping people who cannot afford insurance.
Wasserman Schultz discovered a lump in her breast in 2007 and has undergone seven cancer-related surgeries, including a double mastectomy.
Under Obama's health law, insurers cannot refuse anyone because of past poor health.
—This post was updated at 4:48 p.m.