Former Mayor Michael R. Bloomberg of New York City said this week that he would run millions of dollars in political television ads against four state attorneys general who are suing the Obama administration over regulations on power plant emissions.

The ads, which Mr. Bloomberg’s advisers said would cost more than $10 million across the four states, signify a new venture for the billionaire philanthropist, who has already spent heavily from his personal fortune to try to limit the number of coal-burning power plants nationally.

They amount to a defense of the White House over its Clean Power Plan, which has been met with opposition, primarily — but not only — from Republican officials. But Mr. Bloomberg’s goal, his aides insist, is to explain how the issue of clean energy affects people in major cities and living near power plants.

Still, the ads will run in four states that have been presidential battlegrounds, and on an issue that has gained increasing attention from both political parties. The ads will run in Missouri, Florida, Michigan and Wisconsin, and target Republicans and Democrats. The lone Democrat in the group, Chris Koster of Missouri, is running for governor next year.