Big Tobacco might be the immovable object when it comes to resisting tighter legislation and regulation, but the Campaign for Tobacco-Free Kids — despite its relatively small size — is doing a pretty good impression of irresistible force.

As its name suggests, the group is intent on cutting off tobacco at the roots by expending its $15 million annual budget on efforts to keep the young from acquiring the habit of smoking or chewing the stuff .

Started in 1996 with funding from the American Heart Association, the American Cancer Society and the Robert Wood Johnson Foundation, the nonprofit says it is the best-funded anti-tobacco group in the United States. Its 82-person staff also has established programs worldwide, thanks to funding from Bloomberg Philanthropies that doubled its size.

Campaign President Matthew L. Myers says he’s been driven to prevent smoking among the young ever since he led a 1980 Federal Trade Commission investigation based on the first federal subpoena of a large volume of industry documents.

“We got a look inside the industry to recognize the extent to which the industry marketing both targeted young people and undermined the government’s health message,” he said.

In the three decades since, the industry has agreed to pay states tens of billions of dollars to settle Medicaid suits seeking funds to treat tobacco-related illness.

In 1998, the industry agreed with state attorneys general not to market to children and youths. And in 2009, it came under a comprehensive Food and Drug Administration regulatory scheme after President Barack Obama signed a law giving the agency the power to regulate tobacco.

Even so, the industry continues to find ways to market to teens, Myers says. Cigars marketed with flavors such as candy, fruit and chocolate have become a hit among teens even as their cigarette use drops. In Massachusetts, for example, 16 percent of high school boys smoke cigarettes, but 20 percent smoke cigars, according to the campaign.

“If a loophole is left in the law, they will fill it,” Myers says. As persistent as the industry is, however, the campaign and other anti-smoking advocates and programs are part of what Myers calls a “true American public health success story.” The group has lobbied for higher tobacco taxes, graphic warning labels, marketing curbs and laws to prevent indoor smoking — proven tactics to lower tobacco use, he says.

“In just the last 15 years, we’ve seen smoking rates among high school students go from over 36 percent to just barely over 17 percent. We’ve seen a drop in smoking rates among minority groups across the board,” Myers says.

“We’ve seen a complete change in the rules governing where people smoke. In 1990, there wasn’t a single state that prohibited smoking in workplaces or restaurants and bars. Today, the vast majority of Americans live in states or cities where smoking isn’t allowed where they work, or where they eat, or where they go to recreate.”

The FDA has the authority to crack down on flavored cigars, too, and on products that previously were called cigarettes and are now called little cigars, Myers says. What’s needed is public pressure on the agency to act. Publicizing the rising rate of flavored cigar use among the young will help build up that pressure, he says.

“The progress that we’ve made is real, substantial and has saved literally millions of lives,” Myers says. But “the fact that tobacco use remains America’s No. 1 preventable cause of premature death shows just how far we still have to go.”