BOSTON — U.S. Sen. Edward Markey is co-sponsoring a bill by Sen. Bernie Sanders that would guarantee everyone in the country is covered by health insurance.

Markey joins fellow Massachusetts Democratic Sen. Elizabeth Warren in backing the bill introduced Wednesday by the independent Vermont senator. The bill would create a federal “single-payer” health care system.

Under the bill, every resident of the United States would receive health insurance through an expanded Medicare program.

Markey says most wealthy countries already provide universal health insurance.

On his website, Sanders says his plan would be funded in part by higher taxes on the wealthy and a 6.2 percent income-based health care premium paid by employers.

Sens. Richard Blumenthal of Connecticut and Sheldon Whitehouse of Rhode Island — both Democrats — are also co-sponsoring the bill.