The political world is understandably focused on the presidential race, which is tighter than ever as Vice President Kamala Harris gains ground on former President Donald J. Trump.

And while whoever occupies the White House for the next four years will have a big impact on the nation’s climate policy, a topic that we explored in June, many of the down-ballot races will also be consequential in determining how fast the United States transitions away from fossil fuels. Take, for example, Arizona and Montana, where elections to commissions that regulate utilities will help determine just how fast those states embrace renewable energy.

“Whoever is in the White House matters,” said Laurel Javors, associate director for state and local politics at the Sierra Club. “But a lot of climate work also comes down to local elections.”

Congress

Of paramount importance, climate activists say, is who controls Congress. The president can only do so much to bend the emissions curve without a House and a Senate that can champion climate policy like the Inflation Reduction Act, which is unleashing billions of dollars in clean energy investment.

With the Senate controlled by Democrats and the House controlled by Republicans, both by narrow margins, congressional elections in November will go a long ways to shaping the next four years of climate action in the U.S.

And in some of the most closely watched races in the country climate is a campaign issue.

In Pennsylvania, Dave McCormick, a former hedge fund executive running as a Republican and challenging Senator Bob Casey, a Democrat, has made fracking a central issue of the campaign. Casey has been an outspoken champion of clean energy, while Mr. McCormick, who has been endorsed by Trump, has pledged to support fracking.