President Barack Obama will Monday unveil what he called the "biggest, most important step we've ever taken" to fight climate change, a sensitive issue central to his legacy.

The White House will release the final version of America's Clean Power Plan, a set of environmental rules and regulations that will home in on the pollution from the nation's power plants, setting limits on power-plant carbon emissions.

Laying out how climate change was a threat to the health, wellbeing and security of millions of Americans, and adding that time was of the essence, Obama said in a video released early Sunday: "Climate change is not a problem for another generation. Not anymore."

"Power plants are the single biggest source of harmful carbon pollution that contributes to climate change," added Obama, who made the battle against climate change a core promise of his 2008 election campaign.

"But until now there have been no federal limits to the amount of that pollution that those plants can dump into the air."

He added that without imposing limits, "existing power plants can still dump unlimited amounts of harmful carbon pollution into the air weekly.

"For the sake of our kids, for the health and safety of all Americans, that's about to change."

Obama argued that the plans will lead to lower energy bills for everyday Americans and create jobs in the renewable energy sector.

Quite simply, he said, the United States needed to lead the world in saving the planet, ahead of a major meeting of world powers in Paris in December tasked with doing just that.

- Politically sensitive -
The new plan sets a goal of cutting carbon pollution from power plants by 32 percent by 2030, compared with 2005 levels, The Washington Post said. Previously the target had been 30 percent.

But the move is likely to face fierce opposition from numerous sides, including political rivals and industry groups, as well as possible legal challenges.

Power plants account for some 40 percent of US emissions of carbon dioxide, the most common greenhouse gas that contributes to climate change.

Cuts are politically sensitive as coal, among the dirtiest energy sources, remains a major US industry.

The Washington Post quoted an unnamed White House official as saying: "This is the most significant action any US president has taken to curb greenhouse gases.

"It will form the foundation of the country's efforts to take on climate change for decades to come."

But even as natural gas gains in popularity, coal remains a key component in the American energy landscape.

Hundreds of coal-fired power plants dotted across the country provide about 37 percent of the US electricity supply, ahead of natural gas and nuclear reactors.