The last time Vice President Kamala Harris tried to win the White House, she staked out aggressive positions on climate change, calling for a ban on fracking, a tax on carbon pollution and $10 trillion in spending to fight global warming. But one past action stands out as something that could be both an asset to Ms. Harris as well as an albatross.

As a senator in 2019, Ms. Harris cosponsored the Green New Deal, a nonbinding resolution that was centered around the idea that addressing climate change required significant changes in the economy. It called for converting the electric grid to 100 percent clean energy this decade, declared clean air, clean water and healthy food to be basic human rights. But it also endorsed free health care and affordable housing for all Americans.

Different variations of a Green New Deal had been circulating in Europe and in progressive circles in the United States for years before Senator Edward J. Markey, Democrat of Massachusetts, and Representative Alexandria Ocasio-Cortez, Democrat of New York, made a first effort to get Congress to endorse the idea. Ms. Harris joined them.

“Climate change is real, and it poses an existential threat to us as human beings, and it is within our power to do something about it,” Ms. Harris told a New Hampshire crowd in 2019 when she was seeking the Democratic nomination for president. “I am supporting the Green New Deal,” she said to thunderous applause.

Republicans framed the Green New Deal as a socialist takeover that would bankrupt the nation. They held a procedural vote in the Senate in March 2019, where it failed 0 to 57, with all Republicans voting against allowing a full vote and 43 Democrats voting “present.”

When Joe Biden became the Democratic nominee in 2020 and tapped Ms. Harris as his running mate, he distanced himself from the Green New Deal. Ms. Harris followed suit.