A proposal considered by California lawmakers would substantially remake the health care system of the nation's most populous state by eliminating insurance companies and guaranteeing coverage for everyone.

The idea known as single-payer health care has long been popular on the left and is getting a new look in California as President Donald Trump struggles to repeal and replace former President Barack Obama's health care law.

The proposal, promoted by the state's powerful nursing union and two Democratic senators, is a longshot. But supporters hope the time is right to persuade lawmakers in California, where Democrats like to push the boundaries of liberal public policy and are eager to stand up to the Republican president.

Hundreds of nurses are planning to rally Wednesday in Sacramento before a hearing in the Senate Health Committee.

"We have the chance to make universal health care a reality now," Democratic state Sen. Ricardo Lara of the Los Angeles-area city of Bell Gardens said last month. "It's time to talk about how we get to health care for all that covers more and costs less."

The measure would guarantee health coverage with no out-of-pocket costs for all California residents, including people living in the country illegally.

Private insurers would be barred from covering the same services, essentially eliminating them from the marketplace. Instead, a new state agency would contract with health care providers such as doctors and hospitals and pay the bills for everyone.

However, an essential question is still unanswered: Where will the money come from? California health care expenditures last year totaled more than $367 billion, according to the Center for Health Policy Research at University of California, Los Angeles.

The measure envisions using all public money now spent on health care — from Medicare, Medicaid, federal public health funds and "Obamacare" subsidies. But it would also require tax increases on businesses, individuals or both.

Lara, who wrote the legislation with Democratic Sen. Toni Atkins of San Diego, says they are working on the details.

Employers, business groups and health plans have mobilized in opposition, warning that the measure would require massive tax increases and force patients into lengthy waits to see a doctor.

They say the state should stay focused on implementing Obama's health care law, which is credited with significantly reducing the ranks of the uninsured in California.

"California can't afford a single-payer health care system," said Charles Bacchi, president and CEO of the California Association of Health Plans. "It's going to reduce the quality of care. We think it will restrict access to care, and it will be incredibly disruptive to all the Californians who currently get health care coverage through their employer."

The idea faces significant hurdles.

The legislation, SB562, would affect everyone — not just the roughly 8 percent of Californians without insurance — including people on Medicare and private, employer-sponsored insurance, plans that are generally well-liked.

Replacing billions of dollars in health care spending by employers and individuals would require significant tax increases, which must have support from two-thirds of the Assembly and Senate.

Even if it were to clear the Legislature and be signed by Democratic Gov. Jerry Brown, it would require cooperation from Trump's administration to waive rules about federal Medicare and Medicaid dollars.

The idea to substantially increase the government's role in health care comes as Trump and Republicans in Congress look to reduce it. The conservative House Freedom Caucus on Wednesday announced its support for a newly revised GOP health care bill, a month after the group's opposition forced Republican leaders to pull the legislation.