Democrats in the US Senate are expected to unveil a bill to help reduce greenhouse gas emissions over the next four decades, in a move which could boost President Obama's aim to tackle global warming.
The Senate Democrats' draft legislation embraces major elements of a controversial bill that passed the House of Representatives in June.
Both bills would establish a "cap and trade" system for replacing fossil fuels with cleaner solar, wind and other alternative energies to power factories and oil refineries and produce electricity.
Unless the draft bill is changed last-minute, Senators Barbara Boxer and John Kerry have written a measure that aims to reduce smokestack emissions of carbon dioxide by 20% by 2020 and 83% by 2050 from 2005 levels.
The short-term goal is slightly more ambitious than the House's 17% target, writes Reuters.
The US Congress has previously been criticised by many countries for advancing legislation that does not sufficiently address concerns about climate change, especially with a December deadline looming for an international deal when world leaders meet in Copenhagen.