Rep. Lindsay Sabadosa, Sen. Jamie Eldridge, and Rep. Denise Garlick, lead sponsors of single-payer health care bills this session, testified about their proposals Tuesday before the Health Care Financing Committee. SHNS PHOTO

BOSTON — Lawmakers proposing that Massachusetts adopt a single-payer health care system were grilled Tuesday by one of their powerful Democratic colleagues, who said she’s a “big believer in single-payer health care” but that moving from theoretical support to implementation becomes “dicey.”

“The complexity is not as simple as the tagline ‘Medicare for all’ for us,” Health Care Financing Committee Co-chair Rep. Jennifer Benson told sponsors of single-payer legislation at a hearing on their bills. “The federal government needs to expand Medicare, period. That is the right solution that could be done easy, so to speak, but we have to create an entire new system and answer those questions on our own.”

Sen. Jamie Eldridge, Rep. Lindsay Sabadosa and Rep. Denise Garlick have filed a pair of bills (H 1194, S 683) that would establish a government-run single-payer or “Medicare for all” system to provide health care to all Massachusetts residents, funded through a payroll tax.

With nine other lawmakers behind them, they told personal stories about challenges accessing care and said single-payer would make health care more equitable, simplify the system, and provide better access to treatment for addiction treatment, reproductive health and mental health services.

After they wrapped up, Benson and other committee members peppered them with questions on issues including costs, implementation timeline and details, the handling of out-of-state residents who work in Massachusetts, when and whether the state would be able to get a Medicaid waiver from the federal government, and what happens if a Massachusetts resident needs extensive medical care in another state.

Sen. Cindy Friedman, the committee’s Senate chair, said the panel needed answers to those questions to “bring the public along with us” through honesty about what single-payer would look like and the trade-offs involved.

“I just don’t want to set up this idea that if we go to Medicare for all, if we go to single-payer, that all of a sudden everybody’s going to have access to every single thing they need when they want it, if they want it,” said Friedman, an Arlington Democrat. “And I think part of what we have to do in order to get to this, to a single-payer system, is to bring the public along with us and the only way we can do that is by being really transparent.”

Drawing a chorus of approving finger-snaps from the crowd, Eldridge said supporters of the bill are arguing for a “totally revolutionary system” because “playing around the edges is not going to address costs.”

In response to a question about costs from Rep. Steve Ultrino, Eldridge said studies have indicated the payroll tax would be less expensive than costs associated with the current system, including copays, deductibles and premiums.

Eldridge, an Acton Democrat, said he suffered a major seizure 10 years ago and spent six weeks in the hospital and a rehabilitation center. It took him three years to pay off his medical bills, he said.

“That really shows how broken this health care system is,” he said.

Sabadosa, a Northampton Democrat, said the day an oncologist found 27 small tumors in her partner’s lungs and then said their health insurance wouldn’t cover treatment at that hospital “changed my life.” She said her partner ultimately went to Italy, where his family lived, for some of his treatment, and single-payer became “one of the biggest issues” when she ran for office last year.

The bills filed by Sabadosa, Garlick and Eldridge would would make it state policy to provide access to health care services to all residents as a right, “without co-insurance, co-payments or deductibles,” through a new Massachusetts Health Care Trust.

Any federal health care funds and revenues from a 7.5 percent employer payroll tax, a 2.5 percent employee payroll tax, and a 10 percent tax on self-employed payroll and unearned income would go into the trust. The first $30,000 in payroll for employers and the self-employed would be exempt, and employers with 100 or more workers would face an additional tax of 0.44 percent.

More than 60 lawmakers, including Benson, are signed on to Sabadosa’s bill, and Friedman is among the nearly 40 cosponsors of Eldridge’s bill.

Single-payer supporters told the committee of their struggles to pay for health care – 17-year-old Calvin Tompkins said he’s expecting to pay $25,000 a year for insulin once he turns 18, and he’s discussing with his parents if he can afford to go to college – and of their experiences with single-payer systems in other countries.

Maria Termini, an artist and activist from Roslindale, said she was once bitten by a dog in Bolivia, where she paid $35 each for her first four rabies shots. Back at home in the U.S., the fifth shot cost her $1,200.

“We need to understand that exploiting sick and suffering people to make a profit is wrong,” Termini said. “That’s why we need a nonprofit, simple, single-payer system, improved Medicare for all.”

Lora Pellegrini, president and CEO of the Massachusetts Association of Health Plans, said in a statement that debate around adopting a single-payer system “only distracts from the critical work we must do to control health care costs for employers and consumers across our state.”

“Mandating a one-size-fits-all, government-run health care system will eliminate health care options for patients and ignores our state’s universal coverage achievements,” said Pellegrini, who noted that almost 98 percent of Massachusetts residents have health insurance coverage. She said other states that have studied single-payer health care have rejected it “because the significant tax increases needed to support the system would leave the state uncompetitive, crippling economic growth and job creation.”

A bill filed by Rep. Kate Hogan (H 1163) would create a commission to investigate “the methods, cost and feasibility of establishing single payer health care in the commonwealth” and produce a report by June 30, 2020.

Hogan said she wants Massachusetts to avoid “pitfalls” experienced in states like Vermont and New York where single-payer attempts have been unsuccessful and to “build a viable, resilient system that works for our state.”

“I need to be able to tell my constituents that I know the single payer system we adopt will cut costs and be more affordable and accessible – all the while sustaining the Commonwealth’s high-standard of care,” the Stow Democrat said.

Critics objected to the inclusion of health plan representatives and other health care industry groups on the commission.

“This commission is stacked with opponents of single payer and doesn’t reserve a seat for representatives of nurses, healthcare workers or single-payer advocates,” said Matt Miller of the group Act on Mass.

Jonathan Cohn of Progressive Massachusetts, who testified for the Eldridge/Sabadosa bills and against Hogan’s, said a state study isn’t needed to know where the insurance industry stands on single-payer.

“We can Google that,” he said.