WASHINGTON — A health care proposal from Senate conservatives would let insurers sell skimpy policies provided they also offer a comprehensive plan. It’s being billed as pro-consumer, allowing freedom of choice and potential savings for many.

But critics say it would split the sick and the healthy, leading to unsustainably high premiums for people with medical problems and pre-existing conditions, who may get priced out of the market unless taxpayers bail them out.

Senate Republican leaders trying to resolve differences between moderates and conservatives ahead of a health care showdown are taking a close look at the proposal from Sens. Ted Cruz, R-Texas, and Mike Lee, R-Utah, dubbed the Consumer Freedom Amendment. No final text has been made public, but the concept has been endorsed by Vice President Mike Pence.

A health care factoid can help frame the issue: U.S. health care spending is highly skewed toward the sickest people. According to government estimates, 5 percent of the population accounts for nearly half of health care spending. And half the population — the healthier half — accounts for only about 3 percent of spending. The traditional idea behind insurance is that the healthy subsidize the sick.