RICHMOND — Gov. Ralph Northam vetoed three bills intended to expand access to health insurance this week as he wrapped up work from this year's regular General Assembly session, expressing concern that the measures could have weakened the Affordable Care Act.

The vetoed bills were sponsored by fellow Democrats and passed both chambers with broad bipartisan support.

Two were identical House and Senate measures that would have allowed self-employed people to buy insurance through professional groups, such as Realtors’ associations. The third was a Senate bill that would have permitted small businesses to band together to buy group health insurance for their employees.

In announcing the vetoes, Northam’s office issued a statement suggesting that the measures could have undermined the ACA by providing an alternative to buying coverage on the insurance exchange, which could lead to higher costs for those who remained. Northam won office in 2017 on a promise to expand Medicaid under the ACA, which has allowed more than 420,000 uninsured Virginians to get health coverage.

“Governor Northam’s administration has worked to expand access to affordable, quality care for all Virginians,” the statement said. “The vetoed bills would address health insurance cost concerns for targeted segments of the population, but in doing so, could increase the cost of insurance for sicker Virginians in the marketplace.”

Republicans blasted Northam’s action.

“Governor Northam today reaffirmed his commitment to a government-only, ‘one-size-fits-all’ approach to healthcare coverage for Virginians,” said a statement from Senate Minority Leader Thomas K. Norment Jr. (R-James City) and the chamber’s other GOP leaders.

House Republican leaders, including Minority Leader Todd Gilbert (R-Shenandoah), issued a statement of their own that said Northam’s vetoes “were directly opposed to his claimed priority of improving health care access for Virginians. . . . Governor Northam simply doesn’t want Virginians to have a choice in healthcare.”

Even some usual Democratic allies said they were deeply disappointed.

“It was very, very frustrating,” said Sen. George L. Barker (D-Fairfax), who carried the Senate version of the bill sought by Realtors and other self-employed workers.

Barker said he’d worked closely with Sen. Siobhan Dunnavant (R-Henrico) when she’d brought a similar bill a year earlier. The administration had raised concerns that Dunnavant’s measure would not comply with certain ACA mandates, such as a requirement that coverage not be denied for preexisting medical conditions.

This time, Barker sponsored the bill and said he made sure it fully complied with the ACA. He said he had several meetings with administration officials over the past year to discuss any concerns.

“We’d have meetings, and they’d say, ‘This is interesting. We’ll get back to you and give you some suggestions,’ which they never did,” he said. “We addressed all the issues they raised last year.”

Northam’s spokeswoman Alena Yarmosky declined to comment beyond the news release.

Northam’s vetoes did get cheered in some quarters, including AARP.

“We are tremendously grateful that Gov. Northam took action to stop legislation that would have negatively affected older people and could have caused the health care marketplace to become even more unstable in Virginia,” Jim Dau, the group’s Virginia director, said in a written statement.

The other vetoed bills were sponsored by Del. Chris L. Hurst (D-Montgomery) and Sen. T. Montgomery “Monty” Mason (D-Williamsburg).

After the General Assembly adjourned March 12, Northam signaled his opposition to the measures by proposing amendments that would have required them to pass the General Assembly a second time before taking effect. Barker called that an attempt to kill his bill when the legislature met to consider his amendments or any vetoes at its one-day “veto session” in April.

The House and Senate rejected the amendments and sent the bills back to Northam, who had to choose between signing them in their original form or vetoing them.

Northam vetoed one other bill earlier this year, a measure sought by the dairy industry that would have defined milk as coming only from a cow or other mammal.