RICHMOND — Gov. Ralph Northam (D) angered environmental groups Thursday by signing off on a state budget that includes language hampering Virginia’s ability to participate in a regional program to limit carbon emissions.

The environmentalists had urged Northam to use a line-item veto to remove the budget provision, inserted by Republicans to keep Virginia out of the Regional Greenhouse Gas Initiative. Advocates say the program could reduce the state’s carbon emissions by 30 percent.

"This was a disastrous and cowardly retreat by Northam," Walton Shepherd, Virginia policy director for the Natural Resources Defense Council, said via email. "Instead of protecting Virginians with his clear veto authority, he rolled over, not only for big polluters, but also for a climate-denying fringe of the legislature."

Northam lamented the situation in a news release announcing his signature on the $119 billion two-year spending plan, calling the carbon-cap restriction a “disappointing and out-of-touch” provision. But his advisers apparently believed he lacked the legal authority to veto that language.

The governor said there were other aspects of the budget that he also disliked, including limits on using state funds for abortions in cases of extreme fetal abnormalities and restricting state agencies from buying and using body-worn cameras.

He said the provisions “do a disservice to the citizens of the Commonwealth,” and vowed not to be “constrained” by them when he puts together a new budget this fall.

But that wasn’t good enough for environmental advocates, several of whom said that they had thought Northam was prepared to veto the carbon cap language and that it was legally defensible.

The RGGI is a market run by nine states in the Northeast that sets limits on carbon emissions by major industrial producers. Plants that lower their emissions can sell allowances to others who might exceed the carbon caps.

Northam has praised the effort, and earlier this year vetoed a bill passed by the Republican-controlled General Assembly that would have prevented the governor from entering into the initiative. But the budget language still prevents the state from spending any money to participate.

By law, Virginia governors have limited powers to veto individual lines in the state budget. Any vetoed language cannot be tied to an underlying budget expenditure, and the clerk of the House of Delegates must rule on whether such vetoes are acceptable. The General Assembly has sometimes simply ignored vetoes of budget line-items, such as when Northam’s predecessor, Terry McAuliffe (D), tried to reject budget language aimed at stopping the expansion of Medicaid.

Alternatively, if the clerk approved the veto, the General Assembly could challenge it in court.

Even McAuliffe put pressure on Northam to act on Thursday, tweeting a reminder that he had paved the way for joining the regional carbon initiative with an executive order.

“The GOP has snuck language into VA budget to reverse that historic action,” McAuliffe tweeted. “This attack on the environment must be stopped.”

House Speaker Kirk Cox praised Northam’s action on the budget. “I am pleased the Governor is recognizing the constitutional authority of the General Assembly to set conditions and restrictions on appropriations,” Cox (R-Colonial Heights) said in a news release. “I hope the Governor’s deference today will make future governors think twice before attempting to trespass on legislative prerogatives.”

A spokeswoman for the governor said Northam did not see the need for a legal showdown with legislators. “The speedier remedy for these out-of-touch provisions is the election of Democratic majorities in November,” spokeswoman Ofirah Yheskel said via text message.

In the meantime, Yheskel said, the state Department of Environmental Quality will look for ways to implement carbon-reduction plans. The state’s Air Pollution Control Board authorized such steps last month in anticipation of participating in the regional cap-and-trade marketplace.

All 140 seats in the General Assembly are on the ballot this fall. Republicans hold two-seat majorities in each chamber, and Democrats are hoping to flip them both.

Democratic momentum has been slowed since February, though, when all three executive branch leaders — Northam, Lt. Gov. Justin Fairfax (D) and Attorney General Mark Herring (D) — were crippled by scandals. Northam and Herring have admitted blackface incidents from decades ago, while Fairfax has strongly denied charges of sexual assault levied by two women over alleged incidents from 2000 and 2004.

The situation has hampered the leaders’ ability to raise money for the legislative elections and raised questions about their remaining political clout.

“I doubt we’d be in this situation if it weren’t for the blackface scandal,” said one environmental activist, who spoke on the condition of anonymity to address the sensitive subject. This person said Northam’s diminished status prevented him from facing down Republicans over the veto.

Shepherd, of the NRDC, said the “inexplicable abdication of duty sows further doubts about his capacity to lead.”

Environmental groups have been among Northam’s top campaign supporters. Aside from a Democratic Party organization, the Virginia League of Conservation Voters was the most generous donor to Northam’s election in 2017, at almost $2.9 million, according to the nonpartisan Virginia Public Access Project.

“Virginians elected Northam, in part, because he promised to take serious climate action,” the league’s executive director, Michael Town, said Thursday via email. “Today, he failed to live up to that promise.”