Earlier this week, Senator David Vitter, a Louisiana Republican, said that he would drop his threat of a filibuster and allow an up-or-down vote on Gina McCarthy, President Obama’s nominee to lead the Environmental Protection Agency. This is welcome news, not just for the agency but for the planet. More than any other federal official, Ms. McCarthy will be responsible for carrying out Mr. Obama’s promise to confront the threat of climate change.

Her main weapon will be her authority under the Clean Air Act to regulate emissions from power plants, which account for about 40 percent of America’s emissions of carbon dioxide, the main greenhouse gas. The agency has aggressively sought to control ground-level pollutants like mercury, but regulating atmospheric pollutants from power plants and other stationary sources is uncharted territory. Devising an effective program will require negotiations with industry and state governments, which will be largely responsible for figuring out how to meet the emissions standards she imposes.

Ms. McCarthy, who has spent the last few years in charge of the E.P.A.’s clean air programs, would seem ideally suited to this task. A first-class negotiator, she has occupied important state-level policy jobs under Republican governors in Connecticut and Massachusetts (including Mitt Romney, in his environmentally progressive phase). She has allies in the business community, and even Mr. Vitter did not object to her personally. His complaint was with the agency and what he said was its past failure to provide data to support its regulatory decisions.

Ms. McCarthy must also enforce other contentious laws, including the Clean Water Act. The job has a history of exhausting its occupants, whatever their party. But the chances seem good that with White House backing — always an issue in this job — she will carry it off.