Democratic presidential hopeful Rep. Tulsi Gabbard declined Wednesday to back the "Green New Deal," citing "concerns" about it.

"I have some concerns with the Green New Deal, and about some of the vagueness of the language in there, so have not co-sponsored the legislation," the Hawaii congresswoman said when asked about the progressive plan to rapidly shift away from fossil fuels to fight climate change.

Gabbard's position on the nonbinding resolution from Rep. Alexandria Ocasio-Cortez (D-N.Y.) and Sen. Ed Markey (D-Mass.) is a contrast from her position three months ago.

She spoke at a Capitol press conference in November to support the Green New Deal, alongside Ocasio-Cortez, other Democrats and youth activists.

"I am proud to stand here together with our friends, our allies, our colleagues, to fight for a green energy economy, the [Off Fossil Fuels] Act, other legislation that is there and a Green New Deal," she said at the time.

The Green New Deal was then a draft resolution that called for the creation of a special House committee that would write legislation to eliminate fossil fuels from most of the economy in 10 years, provide a universal jobs guarantee, universal health care and other policies.

The latest iteration, as introduced by Ocasio-Cortez and Markey, would set a goal of net-zero greenhouse gas emissions in the United States, which would effectively mean an end to fossil fuel use in the next decade or so.

Nearly all of the Senate Democrats running for president have backed the Green New Deal. But Gabbard isn't the first Democrat to criticize the it.

Former Rep. John Delaney (D-Md.), a long-shot presidential candidate, called the proposal "about as realistic as Trump saying that Mexico is going to pay for the wall."

Sen. Joe Manchin (D-W.Va.) called it a "dream" in a CNN interview last week.

"You can't just be a denier and say 'I'm not going to use coal, I'm not going to use natural gas, I'm not going to use oil,' " he said.