NASHVILLE, Tenn. >> As a thyroid cancer survivor battling nerve damage and other complications, Lisa Dammert was in such dire financial straits in 2014 that she and her husband did the unthinkable: They let their health insurance lapse for a while.

If the Dammerts and some of the millions of other Americans like them do that under the Republican health care plan now making its way through Congress, they could end up paying a heavy price.

Under the bill, people who go without insurance for even just a couple of months — whether because of a job loss, a divorce, a serious illness that leaves them unable to work, or some other reason — could face sharply higher premiums if they try to sign up again for coverage, especially if they have a pre-existing condition. Some might find themselves priced out of the market.

Dammert, who lives in the Nashville suburb of Franklin, said her husband has since gotten a job that provides health insurance for the family, but she knows hard times could come again. She is watching the fate of the Republican bill.

“It scares me to death,” she said.

The bill, which passed the House but is certain to be amended in the Senate, represents the GOP’s effort to deliver on its promise to repeal and replace President Barack Obama’s Affordable Care Act, a law critics say has driven up insurance costs and is unsustainable.

The bill requires insurers to raise premiums 30 percent for anyone seeking to buy a policy on the individual market who had a lapse in coverage of 63 days or more in the previous year.

The legislation also enables states to obtain a waiver that would allow insurers to charge higher premiums to people with pre-existing conditions if they had a gap in coverage. Under the current law, the sick and the healthy must be charged the same.

Because of those gap-in-coverage rules, some people might be unable to find affordable insurance, according to an analysis by the nonpartisan Congressional Budget Office.

The higher premiums would start in 2019, giving people enough time to get insured and avoid the penalties.

The budget office estimates that states that are home to one-sixth of the U.S. population, or more than 50 million people, would ask for the waiver.

States that opt for a waiver would have to find a way to try to keep premiums affordable, such as creating high-risk pools for people with serious medical problems. In the past, many state-run high-risk pools offered policies that some consumers still found too costly.

“That high-risk pool has to exist, but it does not have to offer affordable coverage,” said Cynthia Cox, associate director of health reform and private insurance at the Kaiser Family Foundation. Insurance companies, she said, could use high premiums to avoid taking on sick people.

Republicans say the gap-in-coverage surcharges will help stabilize premiums for everyone by getting people to carry insurance at all times instead of waiting until they get sick. Michigan Rep. Fred Upton, a Republican, said such provisions are “a simple but important reform that will encourage patients to enroll in coverage and stay enrolled.”

Yet maintaining health insurance might not be possible all the time, said Albert Noll, a speech pathologist in Austin, Texas.

Before Obama’s health care law took effect, Noll and his wife went 15 years with prolonged periods in which they had no insurance. Often, it was just too expensive — as much as $1,250 a month when he worked at a long-term care facility.

“Life happens, and sometimes you are forced into situations, as we have been throughout our lives together, where you (realize), ‘I can’t do this,’” he said. “For whatever reason, it happens to people.”

One three-month gap came after he finished a master’s degree but had to wait for new coverage to kick in. That left them uninsured for part of the time Patricia Noll was pregnant with the couple’s second daughter. She recalls thinking, “Please, God, do not let anything happen.”

Roughly 27 million people had a gap in their health coverage of several months or more in 2015, a recent Kaiser report found. An estimated 6.3 million of those had pre-existing conditions.

Heidi Varner, of Midland Township, Michigan, said her first break in coverage came after a divorce. She worked part-time jobs while raising three daughters but could not afford her own insurance.

She went without coverage for a decade despite having been treated for cervical cancer while on her husband’s plan. She skipped mammograms and other screenings.

The 61-year-old had insurance for roughly eight years while working for the American Cancer Society but was laid off in September. She acquired insurance two months later through Michigan’s expansion of Medicaid, which was made possible by the Affordable Care Act.

Varner said a law that penalizes people for coverage gaps would be out of step with the times.

“In this day and age, there are companies that are downsizing all the time,” she said. “It’s very feasible for most people to have at least a two-month gap in insurance. It’s not like when my dad worked for Dow forever and had a pension and you knew you had a job for your whole life.”