Marnie Miller wasn't sure she supported having a public plan option included in health reform, but she knew she supported having the cost of health insurance lowered.

With that conviction, Miller joined a rally Thursday in Roanoke to ask Sen. Mark Warner to support a public plan as Congress considers how to restructure health insurance for the nation.

"I don't know much about the politics," Miller, of Roanoke, said. "But I don't have health care because of the high cost."

Neither Miller nor her five children have health insurance. When they are sick they go to the emergency room.

A registered nurse and a single parent, Miller said she earns too much for her children to qualify for health insurance through the state, but not enough to afford the high cost of insurance.

"It would be $1,000 a month," she said.

Like Miller, many of the approximately two dozen people gathered Thursday couldn't articulate the exact details of what a public option entails. Instead they talked about the outcomes they are interested in seeing, such as making insurance more affordable and eliminating the increased expense associated with having a pre-existing condition.

"I want everybody to be able to afford coverage regardless of employment status," said Nathan Auldridge, who organized Thursday's rally. "And a public plan would do that, and it is the way to drive down the cost."

Defining a public plan is difficult partly because it isn't clear what Congress will deem as a public plan.

For many health care reform advocates, a public plan is a government-backed insurance policy that negotiates rates and provider networks similar to any private insurer. That fits Auldridge's definition.

But others relate a public plan to universal coverage similar to a European system or a single-payer option where everyone is covered under one plan. And some say it is expanding government-run insurance plans like Medicare and Medicaid. Still others say it is an insurance exchange where citizens can buy into the federal employee health benefit plan.

It's the confusion over what a public plan will look like that has made Warner hesitant to take a firm stance on supporting the public option, said Kevin Hall, Warner's spokesman.

While Warner has said he does not support a single-payer option, he has not discounted supporting a public plan.

"Sen. Warner is closely examining the bill as it continues to take shape," Hall said. "He is interested in seeing a mixed public and private plan that will encourage competition while providing a level playing field."

Auldridge, 25, of Salem, led the participants from the Martin Luther King Jr. statute in Roanoke's Gainsboro neighborhood to Warner's office on Salem Avenue.

Auldridge presented Warner's staff with a 151-page petition with an unknown number of signatures from across the state. The petition was complied online by the liberal group MoveOn.org.

Miller told her story of needing health insurance, and Auldridge shared a similar account of affording coverage. Having had a brain tumor removed in 2006, Auldridge can't afford to go without health insurance.

"I would have a pre-existing condition," he said.

So he pays, with help from his mother, $465 a month, to stay insured.

A theater major in college, Auldridge doesn't have steady work. Instead, he said, he hopes to make a movie about his experience with the brain tumor, and works odd jobs as a stage hand when he can find something.

In April, Virginia Sen. Jim Webb signed a letter along with 15 other U.S. senators calling for a public plan. The letter outlined how a public plan could lower health costs, improve quality, ensure access to rural areas and bring competition among insurance companies.

Calls to Warner's office about supporting the public health plan have been fairly consistent, with about 400 coming in a week, Hall said.

On Thursday between 9 a.m. and 3 p.m., Warner's office fielded 63 calls. While this week has brought out more people in support of a public option, last week more people were calling asking Warner to oppose the public option, Hall said.