The federal mandate requiring people to have insurance will end in 2019.
"This is a hugely important proposal," Feldman said. "We're presenting folks with the opportunity to make a rational economic decision."
The measure, which is the first of its kind in the nation, is backed by at least five other Democratic lawmakers, the Maryland NAACP, Baltimore City Health Commissioner Leana Wen and the Maryland Health Care for All Coalition, which helped draft the plan.
Senate Finance Committee Chair Thomas M. Middleton (D-Charles) said his panel will take up the legislation next week. "This is going to set a new high for Maryland," he said. "We have to make sure we make every attempt to make health care affordable."
The other lawmakers who support the plan are Senate Budget and Taxation Vice Chair Richard S. Madaleno Jr. (D-Montgomery), who is running for governor; Senate Deputy Majority Whip James C. Rosapepe (D-Prince George's); House Deputy Majority Whip Bonnie Cullison (D-Montgomery) and Del. Robbyn Lewis (D-Baltimore City).
Proponents of the plan said they're hopeful that Gov. Larry Hogan (R) will support it, noting he was one of 10 Republican governors who signed a letter to Congress last year opposing GOP plans to eliminate the federal insurance mandate.
"This is what working for the people of Maryland looks like, particularly when there are threats from the federal government to our health and welfare," Madaleno said.
Hogan said during a news conference on Tuesday that he will keep an open mind. But he expressed reluctance to support any proposal that penalizes residents for not purchasing insurance.
"I'm in favor of providing incentives rather than punishment or penalties," he said. "If the legislature has some good ideas about what the state can do to make up for problems where Washington has failed or made mistakes that are going to hurt people in Maryland, we're all ears."
Advocates said they considered proposing a state insurance mandate but decided to push for a down-payment system instead, hoping to avoid the type of conflict that surrounded the federal requirement enacted under the Obama-era Affordable Care Act.
Under the plan they introduced Tuesday, the state would notify uninsured residents starting in 2020 that they will be charged a fee to help them obtain coverage through the state's health-care exchange. Residents would also have the option of paying the penalty and receiving nothing in return.
If coverage is available for the cost of the fee plus any federal assistance for which the individual qualifies, the state would enroll that person in the plan at no additional cost.
If the funds are not adequate for enrollment, the state would place the money in an escrow account to help the resident obtain coverage during the next available enrollment period.
A "use it or lose it" rule would apply to escrow funds that have not been used for insurance by the end of open enrollment.
Uninsured residents who are eligible for Medicaid would be automatically signed up for the program without a fee.
Advocates estimate that more than 200,000 Marylanders qualify for insurance on the state's exchange, and that many would qualify for federal assistance because their employers do not provide coverage.
Feldman and Peña-Melnyk chaired a commission created last year by the Democratic-majority legislature to determine the possible impacts of changes to the Affordable Care Act after President Trump took office and pledged to repeal the law.