GOV. CHARLIE BAKER threw in the towel on his transportation climate initiative on Thursday just days after Gov. Ned Lamont of Connecticut did the same thing in his state.

“The Baker-Polito Administration always maintained the Commonwealth would only move forward with TCI if multiple states committed, and, as that does not exist, the transportation climate initiative is no longer the best solution for the Commonwealth’s transportation and environmental needs,” said Terry MacCormack, the governor’s press secretary, in a statement.

Lamont indicated he might revisit joining the initiative after next year’s election, but Baker’s statement indicated he intends to move on and not look back. It’s a stunning turnaround for a concept that once attracted the interest of a dozen northeast and mid-Atlantic states and became a linchpin of the Baker administration’s plan for reaching net zero greenhouse gas emissions by 2050.

Katie Theoharides, the governor’s secretary of energy and environmental affairs, said in December 2020, when Massachusetts, Connecticut, Rhode Island, and the District of Columbia announced they were moving forward with the transportation climate initiative, that Massachusetts needed the program if it was going to have a chance of reaching its goal of net zero emissions. “We can’t get there without a program like this,” she said.

She declined comment when asked about the initiative on Thursday after a ceremonial groundbreaking on Cape Cod for the Vineyard Wind offshore wind farm. She said the administration would be issuing a statement on the initiative later in the day.

Massachusetts was the only state supporting the transportation climate initiative until Thursday. The governors in Rhode Island and Connecticut couldn’t get it through their legislatures; Baker had the power to sign on because of earlier legislation giving him the authority to act on his own.

The Transportation Climate Initiative was intended to be a cap-and-invest program for automobile fuels. Fuel wholesalers would purchase at auction allowances permitting them to sell gasoline in Massachusetts and other participating states. The number of allowances would be reduced each year, ratcheting up the price of gasoline and incentivizing drivers to switch to electric vehicles.

Opponents as well as some supporters called the transportation climate initiative a disguised gas tax, but backers said the approach was a nuanced, two-step approach to dealing with climate change by making gasoline more expensive while generating the revenues needed to build the infrastructure needed to transition away from vehicles running on gasoline.

In its statement Thursday, the Baker administration said the federal infrastructure package, the American Rescue Plan Act funding, and state tax revenue surpluses will now become the financing mechanisms for building the infrastructure necessary to reduce transportation emissions and meet the state’s climate goals.

Paul Craney, a spokesman for the Massachusetts Fiscal Alliance, which opposed the transportation climate initiative, said he was glad Massachusetts finally abandoned what he called a “regressive gas tax scheme,”  which he said would have hurt the middle class and the working poor the most. He thanked his allies in the fight — Citizens for Limited Taxation, the Beacon Hill Institute, the National Federation of Independent Business, Massachusetts Republican Party chairman Jim Lyons, and Boston Herald columnist Howie Carr.