 -- After voting for the first time at the age of 55, for Donald Trump, Martha Brawley is worried that the main issue that brought her to the polls, health insurance coverage, is going to become worse.

Brawley, a resident of Monroe, North Carolina, said she fears the new Republican health insurance bill will significantly raise her premiums.

"I'm 55. This is the first time in my life I voted, and I voted for Trump hoping that he would change the insurance so I could get good health care," she told ABC News. "I might as well have not voted."

She first spoke to The New York Times about her concern that she would receive thousands of dollars less in assistance, as tax credits, to help her buy health care coverage under the proposed American Health Care Act (AHCA), dubbed "Trumpcare."

Brawley reportedly receives approximately $8,688 in health care subsidies per year to pay for insurance, but under the proposed bill, she would receive $3,500 a year in tax credits, according to the Times.

AARP, a group that advocates for senior citizens and other older Americans, shares her concern. The organization sent a letter to Congress yesterday saying the proposed bill would "dramatically increase health care costs for Americans aged 50-64."

Many seniors could face a significant increase in health care premiums, since insurance companies will be allowed to charge seniors five times as much as for younger people for a comparable plan. Under the current Affordable Care Act (ACA), insurers are limited to charging three times as much. The tax credits proposed in the AHCA, which would be dispensed mainly on the basis of age and income, would be smaller for older Americans compared with under the ACA, making insurance even more expensive for them.

"Taken together, premiums for older adults could increase by as much as $3,600 for a 55-year-old earning $25,000 a year, $7,000 for a 64-year-old earning $25,000 a year and up to $8,400 for a 64-year-old earning $15,000 a year," AARP said in its letter. The group said a typical senior seeking insurance on a state exchange has an annual income under $25,000.

David Certner, the legislative counsel and legislative policy director for government affairs at AARP, said the plan will "stunningly raise" premiums for older Americans.

"This is a national problem, in terms of the fact that the older and lower income you are, the bigger the premium hike," he told ABC News.

On "Good Morning America," Health and Human Services Secretary Tom Price said, "Our goal is to make certain costs come down."

In response to Brawley's complaints about possible cost increases for her insurance, Price raised the issue of choice.

"We want to make sure she is able to select the physician and treatment that she wants," he said.

When pressed about whether he could guarantee coverage for Brawley, Price cited other aspects of the proposal, including state grants, and said, "You can't pick out one individual and say that individual isn't going to be able to get coverage. Right now people are losing coverage. We have a plan that will allow individuals to pick the coverage that they want and ... the physician and treatment model that they want."

Brawley said she isn't convinced lawmakers understand her challenges and she is waiting to see what happens.

"All these people who talk in politics have insurance. People like me don't," she told ABC News. "They can talk big, and all we can do is step back and hope for the best. We are at their mercy."

ABC News' Brandon Bodow contributed to this report.