 -- Hundreds of California nurses and community activists are rallying today in favor of a bill that could make the state the first to launch a single-payer health care system.

They see this as a chance for the large state to show how a single-payer system can work and illustrate the necessity of providing universal health care coverage, according to Bonnie Castillo, the director of the Registered Nurse Response Network, a project of the union National Nurses United.

"We believe [health care is] a right and not a privilege," she told ABC News. "We know at the federal level there is debate and quandary about what to do, and we know that this provides an opportunity in California to set a standard and a model for the nation."

Supporters of the plan say the timing is right for this kind of legislation in the state, which has enormous influence, with a population of nearly 40 million people and the sixth-largest economy in the world. Health care coverage has been under added scrutiny as Republican leaders in Washington, D.C., have pledged to repeal and replace the Affordable Care Act, leaving many questions about the public's options for health insurance.

This proposed legislation would go further than the ACA by making all California residents eligible for coverage. The bill, the Californians for a Healthy California Act, was introduced by state Sen. Ricardo Lara, D-Bell Gardens, and state Sen. Toni G. Atkins, D-San Diego, last week.

"Healthy California gives everyone insurance, because everyone has a right to health care," Lara said in a statement at the time. "Trump and the Republicans don't get to pick the health care winners and losers, and we'll never get to 100 percent health care in California unless we lead."

If the legislation enacted, California will be the first state to start a single-payer health system in the country. Vermont passed legislation to start a single-payer system in 2009, but the governor scuttled the plan over financing concerns, according to a report in The New England Journal of Medicine.

Castillo said her group is optimistic about the law's chances, since many people have voiced concerns about a possible decrease in health coverage if the ACA is repealed.

"It's different political time. We're just coming off this presidential election where health care was majorly debated and a primary issue," she said. She cited recent studies, including a Pew report released in January that found 60 percent of Americans say the government should be responsible for ensuring health care coverage for all Americans.

This bill does not give details on how California would implement a single-payer system, which would require the state to take on the huge task of negotiating bulk prices for health care services and medications on behalf of the state's giant population. Regardless, she said, her group plans on being at the drafting table to ensure the system can function.

"It's a real opportunity to address this problem and in a way that provides real relief," Castillo said.

A single-payer system would have to overcome unique hurdles in a state where millions of dollars in federal funds are spent on health programs like Medicaid and treatment for veterans.

Without details on how the plan will work with federal programs, it is difficult to say how functional it would be, according to Laurence Baker, a professor of health research and policy and a senior fellow at the Stanford Institute for Economic Policy Research.

"This would have to interact with other national programs," he explained. "The system would have to be functional within the national health system ... It would be another layer of difficulty."

Other countries, like Canada, may have single-payer systems that differ slightly by state or province, he said, but the U.S. is more complicated. Nothing like this plan — a state-run single-payer system that must also comply with federal government rules — currently exists.

"It would have to be a uniquely American California system," Baker said.

It's feasible for California to pull it off, he said, because of its size and bargaining power, but there has never been enough political will to figure out the complex and daunting task of doing so.

"It has been up and down, and it's never been a majority of the population" in support of the single-payer system, Baker said. "In a political sense ... what is the moment for folks who want to support it?"

California's state legislature has considered several health care bills since the early 2000s. It passed a similar bill in 2006, but it was vetoed by then-Gov. Arnold Schwarzenegger, who said socialized medicine was not the answer to the state's health care problems. He subsequently proposed his own universal health care bill, but it was never moved forward.