Barack Obama will unveil a new plan to cut methane from America's booming oil and gas industry ahead of the State of the Union address, in an attempt to cement his climate legacy during his remaining two years in the White House.
The new methane rules – expected ahead of the State of the Union speech next week – are the last big chance for Obama to fight climate change, campaigners said.
"It is the largest opportunity to deal with climate pollution that this administration has not already seized," said David Doniger, director of the climate and clean air programme at the Natural Resources Defence Council.
Methane is the second biggest driver of climate change, after carbon dioxide. On a 20-year timescale, it is 87 times more powerful as a greenhouse gas.
US officials acknowledge that Obama will have to cut methane if he is to make good on his promise to cut US greenhouse gas emissions 17% from 2005 levels by 2020, and by 26% to 28% by 2025.
"It is the largest thing left, and it's the most cost-effective thing they can do that they haven't done already, and all the signs are there that they intend to step forward on that," Doniger said.