Electric vehicles have had a hard year. Sales have been disappointing. Former President Donald J. Trump has regularly disparaged them. And even many environmentally conscious car buyers have been choosing hybrids instead.

Yet the chief executive of General Motors, Mary T. Barra, says the company is still committed to doing away with combustion engine cars in the United States by 2035 — and she may have good reason for her optimism.

G.M. says it will start making money on battery-powered models by the end of the year — becoming the only U.S. automaker aside from Tesla to achieve that feat. Sales of G.M.’s electric vehicles are starting to take off. And the company just introduced a model that sells for less than $30,000 after a federal tax credit.

G.M. and other manufacturers have delayed investment in electric vehicle projects. But in an interview, Ms. Barra rebuffed the notion that the transition from internal combustion has run out of juice. She said G.M. was determined to uphold its 2021 pledge to phase out sales of gasoline cars by 2035 in the United States.

“That is the plan we’re still executing,” she said.

Her expression of resolve comes at a critical moment. Without G.M., the largest U.S. carmaker, it is unlikely that the country can move away from internal combustion engines and the greenhouse gases they emit.