WASHINGTON  President Obama will announce tough new nationwide rules for automobile emissions and mileage standards on Tuesday, embracing standards that California has sought to enact for years over the objections of the auto industry and the Bush administration.

The rules, which will begin to take effect in 2012, will put in place a federal standard for fuel efficiency that is as tough as the California program, while imposing the first-ever limits on climate-altering gases from cars and trucks.

The effect will be a single new national standard that will create a car and light truck fleet in the United States that is almost 40 percent cleaner and more fuel-efficient by 2016 than it is today, with an average of 35.5 miles per gallon.

Environmental advocates and industry officials welcomed the new program, but for different reasons. Environmentalists called it a long-overdue tightening of emissions and fuel economy standards after decades of government delay and industry opposition. Auto industry officials said it would provide the single national efficiency standard they have long desired, a reasonable timetable to meet it and the certainty they need to proceed with product development plans.