Medicaid, the nation’s joint federal-state health insurance program for the poor, is often described as providing a safety net — something to save the neediest people from disaster.

But, as health insurance costs spiral rapidly upward, Colorado lawmakers and health care advocates increasingly say that it is the entire state that is facing a crisis. So, some of them are now proposing a radical, potentially first-in-the-nation idea: Why not let anyone buy their way into Medicaid, regardless of income?

A bill introduced Friday at the state Capitol would instruct several Colorado departments to study the feasibility of that idea, as well as the possibility of creating new public-private partnerships or co-operative health insurance programs. The bill’s sponsors say these would be pro-active measures, as opposed to previous reactive solutions that have tried to smooth the zigs and zags of federal health care policy.

“This is saying, ‘How do we lead on this? How do we find a Colorado solution for our own folks?’ ” said state Sen. Kerry Donovan, a Democrat from Vail and one of the bill’s sponsors.

But the Medicaid buy-in would likely have to be approved by federal officials before it could go into effect, and that may be the smallest of its hurdles. How much would it cost to buy in? How much would the program pay doctors? And how could policymakers guarantee the entire thing would be sustainable, without further eating into the state budget?

The bill has bipartisan sponsorship — all four lawmakers coming from rural areas of the state that have been hit the hardest by high costs and a shrinking number of insurers. But it also has its skeptics, even though it is just a first step.

“Adding more people to the Medicaid rolls doesn’t address the real problem of rising health care costs,” Jesse Mallory, the Colorado director for Americans for Prosperity, wrote in an email.

Already, one out of every five people in Colorado is covered by Medicaid, the result of the state’s early expansion of Medicaid eligibility that is allowed by the Affordable Care Act and largely paid for with federal dollars. Expanding Medicaid even further could weaken the program and, ultimately, hurt the poor and disabled people it was originally designed to help, Mallory said.

Adam Fox with the Colorado Consumer Health Initiative, an advocacy group, said a Medicaid buy-in could provide a reliable, affordable health insurance program and could also create price-lowering competition in counties where there is currently only one private insurer offering plans to people who buy coverage on the state’s exchange. At least two states — New Mexico and Nevada — have already kicked around the idea, but neither has gone much farther than Colorado in making it into a concrete plan.

“It’s important to look at new options for Coloradans,” Fox said.

Mallory, meanwhile, said high insurance costs for many are due to Obamacare regulations, such as the rule that protects people with pre-existing conditions from paying more for insurance.