BOSTON (SHNS) – Almost a month after Gov. Charlie Baker returned sweeping climate legislation to lawmakers with a series of recommended amendments, House Speaker Ronald Mariano said he’s willing to work with the governor on some technical changes but will “not back down on our ambitious emissions reduction targets.”

The bill — which the House and Senate passed for the second time in January after Baker rejected a version sent to him in the final days of the last legislative session — proposes to lock the state into its goal of achieving net-zero carbon emissions by 2050, set interim emission reduction targets, establish appliance energy efficiency standards, authorize additional purchases of offshore wind power and codify protections for environmental justice communities, among other measures.

Baker’s amendments (S 13), which have been before the Senate Committee on Bills in the Third Reading since Feb. 8, address topics including the creation of an opt-in municipal stretch energy code, the 2030 greenhouse gas emissions reduction target, and the sector-specific emission reduction sublimits proposed by the Legislature.

“Nothing substantive will change in this bill,” Mariano said Thursday on WBUR’s Radio Boston.

Mariano, a Quincy Democrat who became speaker in December, said that issues around the COVID-19 vaccine and its distribution are of primary importance to the state right now.

He said the state’s COVID-19 response can be divided into two periods. The closures and other decisions Baker made at the beginning of the pandemic last year “were right on” but now, in the vaccine rollout, there have been “a number of missteps and a number of things that probably could have been done differently,” he said.

There could be “more open communication on the amount of vaccines and how to best access those vaccines,” he said.

Responding to host Tiziana Dearing’s characterization of the Legislature as relatively “hands-off” early on in the pandemic, Mariano said, “We were hands-off because the governor used executive powers at the beginning, and that pretty much takes us out of the equation at the beginning.”

With large swaths of the economy now reopened and vaccine distribution underway, Mariano said there is more of a role for state lawmakers and pointed to the vaccine oversight hearing recently held by the new COVID-19 and Emergency Preparedness and Management Committee.

“We only win when this is behind us and we move into the new normal, so we want to be productive,” he said. “We want to deal with the administration, but we also have a role to make sure things are done effectively.”

At a budget hearing on Tuesday, House Ways and Means Committee Chairman Aaron Michlewitz raised concerns that the small business owners who received grants to help them through COVID-19’s economic turmoil might not know they will face taxes on that money, and Administration and Finance Secretary Michael Heffernan said Baker administration officials are talking with state and federal lawmakers about changing the laws to waive taxes on all state-issued relief payments and some federal Paycheck Protection Program grants.

Mariano said the PPP poses “an interesting dilemma” and that House lawmakers are “working with our friends in the Senate to come up with a solution that hopefully will be coming very soon.”

Former Speaker Robert DeLeo appointed Michlewitz as Ways and Means chairman, and Mariano kept the North End Democrat at the helm of the influential panel when he issued his own leadership and committee assignments last month.

At the start of this term in January, Mariano pledged to assemble a leadership team that would “reflect the growing diversity” in the House, which remains predominantly white and male despite increasing numbers of lawmakers of color and women.

His team includes four women — Majority Leader Claire Cronin, Speaker Pro Tempore Kate Hogan, Second Assistant Majority Leader Sarah Peake and Division Leader Ruth Balser — and one person of color, Rep. Frank Moran, who holds another of four division leader posts.

“You have to deal with what’s available in the body, and I think I’ve done that,” Mariano said when asked if he’d seek to grow the diversity of his inner circle in the future. “We spread it out and tried to get a representative sampling of who’s in the body, and that’s all I can do.”