The California Senate is advancing a single-payer health care plan that would replace insurance companies with government-funded health care for everyone in the state.

The longshot bill cleared a big hurdle Thursday when Senate Democrats voted 23-14 to send it to the state Assembly. But it still faces a tough path forward through the more moderate Assembly.

Proponents acknowledge that their bill is not ready to implement and they're not sure how the $400 billion proposal would be funded. But Democrats say they want to keep it alive so they can continue working out details. Under legislative rules, it would have died if it failed to clear the Senate this week.

Critics warned that the measure would require massive tax hikes and lead to long waits for health care.