The GOP presidential candidate wants to help those who maintain continuous coverage, a fraction of a much bigger group of people at risk of getting turned down because of medical problems.
Here's the catch: If you had a significant break in coverage, an insurer still could delve into your health care record, looking for anything - from a bad back to high blood pressure - that foreshadows future claims. They'd be able to turn you down.
That's a contrast to President Barack Obama's health care law, which guarantees that people in poor health can get comprehensive coverage at the same rates everybody else pays, and provides government subsidies to help low- to middle-income households pay premiums.
Starting Jan. 1, 2014, an insurer "may not impose any pre-existing condition exclusion," the law says.
Romney is stressing his pre-existing conditions plan as he works to soften his public image in the homestretch of a campaign that has tightened since his strong debate performance versus Obama.
"I do have a plan that deals with people with pre-existing conditions," he said during last week's debate.
The Romney campaign has not spelled out details other than it would help those who have maintained continuous coverage. That would entail incremental changes to insurance laws and regulations, and may or may not whittle down the number of uninsured, 49 million nationally.
"It will solve some of the problems," said health economist Gail Wilensky, a longtime adviser to Republicans. "It won't solve the problem of people having gone for a long time without health insurance."
That's because many people aren't able to keep up continuous coverage. Losing health insurance is often connected to major life upheavals like job loss or divorce that drain household budgets. More than 70 percent of the uninsured have been without coverage for a year or longer, according to the Kaiser Family Foundation.
Obama's answer - it's the law of the land unless repealed - is more like hitting the reset button. About 30 million uninsured people would gain coverage as the U.S. moves closer to other economically advanced countries that provide health care for all citizens.
The differences between Obama and Romney reflect a fundamental disagreement about the role of government in dealing with the nation's health care woes: high costs, uneven quality, widespread waste and millions uninsured.
Republicans are looking to individual initiative and private-sector solutions that government can encourage. Under Obama, government has taken the lead, framing a grand bargain in which insurance companies will have to accept all applicants in exchange for a requirement that virtually all Americans carry coverage.
Currently about 13 percent of people age 64 and younger who apply for an individual policy are turned away for medical reasons, according to insurance industry statistics. In 2008, that amounted to more than 220,000 individuals. The denial rate rises to nearly 25 percent for people age 50 to 64.
While Republicans are united in their desire to repeal Obama's law, there is no consensus within the party on how or whether to replace it.
Romney addressed what he'd do about pre-existing conditions in a recent column for The New England Journal of Medicine. "Regulation must prevent insurers from discriminating against people with pre-existing conditions who maintain continuous coverage," he wrote.
But most Americans already enjoy such protection under a 1996 law signed by President Bill Clinton. It works fairly seamlessly for people who switch from one job-based plan to another.
It's harder for people switching from job-based coverage to an individual plan. They first have to exhaust a coverage option known as COBRA, which allows people with job-based insurance to keep their health plan for up to 18 months after leaving the company, provided they pay the full premium. Many can't afford that.
And there's no federal protection against being turned down for a pre-existing condition if you are trying to switch from one individual plan to another.
Romney could plug those two gaps, making it easier for people to switch from job-based to individual coverage and among individual plans. His campaign has not specified how.
In his journal article, Romney also proposed to allow all consumers who purchase coverage individually to deduct the cost from their income taxes, and he expressed support for purchasing pools and for allowing insurers to sell across state lines.
His campaign says states will have the flexibility and resources to design programs for residents who cannot afford coverage on their own.
Individual insurance market expert Karen Pollitz, who served in the Obama administration as a consumer protection regulator, says the components of Romney's plan are unlikely to provide as comprehensive a guarantee as the president's Affordable Care Act.
"The ACA just says insurance companies can't discriminate against you, period," said Pollitz, now with the nonpartisan Kaiser Family Foundation. "If you've been uninsured, you can come into this market on Jan. 1, 2014, no questions asked."