President Richard Nixon, who joined with a Democratic Congress nearly 50 years ago to create the Environmental Protection Agency, said then that clean air and water were “the birthright of every American” and that restoring nature was “a cause beyond party and beyond factions.”

Safeguarding our health and our environment has always enjoyed broad support in both political parties and among the American people. Thanks to the E.P.A.’s diligent work, our air and water are significantly cleaner, and because of that, Americans live longer, healthier lives. It is a heritage from which both parties can draw pride.

But that legacy is now in danger.

The current administrator of the E.P.A., Scott Pruitt, built his political career by attacking clean-air and clean-water rules. Now in charge of the agency, he is tearing down those protections, dismantling the E.P.A., appointing or nominating industry insiders to oversee their former businesses and blocking scientific input.

For the sake of our children’s health, it’s time for Scott Pruitt to go.

Mr. Pruitt is jeopardizing the health and well-being of Americans, and many suspect he is doing it to feed his own political ambition. “You must be running for the presidency,” a conservative radio host said while interviewing Mr. Pruitt in August as he visited Iowa, the state with the first presidential caucuses. The more popular theory inside Washington is that he is lining up deep-pocketed backers to run in 2020 for the Senate seat held by the Oklahoma Republican James Inhofe, who is 83.