The bill actually seeks to do four things: increase insurance affordability; provide consumers with new protections; protect the Affordable Care Act from Trump administration attempts to unravel it; and make sure that private insurers participate in the ACA marketplaces. Some of its provisions apply to all private insurance plans, including employer-sponsored coverage, while others fall on ACA plans alone.

In a January speech, Warren said of the need for stronger consumer protections in health care, "So long as private health insurance exists, we should require these companies to provide coverage that is at least as good and priced as reasonably as the coverage offered by our public health care programs."

Not that Warren has abandoned the notion of single-payer insurance, which has been introduced by Senator Bernie Sanders, I-VT. She's a cosigner of his bill, as he—along with Democratic senators Kamala Harris, CA, Maggie Hassan, NH, Kirsten Gillibrand, NY and Tammy Baldwin, WI—is a cosponsor of hers. In addition, the bill has been endorsed by consumer advocacy organizations Families USA, Public Citizen, Consumers Union and Community Catalyst.

Warren views the bill more as an intermediary measure, since passing a single-payer plan will be a tough sell—but in the meantime, her bill provides protections that will help consumers even as the Trump administration erodes the ACA.

The legislation would switch to a system where premiums are capped as a percentage of income, thus protecting all households against premium increases. It would cap out-of-pocket costs on prescription drugs, and it would also push all private insurers to spend 85 percent of their premium dollars on paying out insurance claims—that's tougher than the requirement ACA plans have to satisfy—and be barred from changing the kinds of drugs that they cover in the middle of the year, as well as how much of those drugs' costs are borne by consumers.

In addition, consumers would be protected from the effects of an insurer dropping a plan during their course of treatment, and insurers would have to notify consumers if a plan no longer covered a particular doctor.

Cost-sharing reductions would be restored under the bill, and funding for outreach and education about enrollment would be increased—and last but not least, insurance companies that bid on Medicare Advantage and Medicaid contracts would be required to offer plans on the ACA marketplaces in parts of the country with limited insurance industry competition.