* Legislation now seen coming "later in September"
* Healthcare debate, Kennedy death cited for delay
* China, India, other countries watching U.S. progress (New throughout)
By Richard Cowan
WASHINGTON, Aug 31 (Reuters) - U.S. Senate Democrats announced on Monday a new delay on climate change legislation, which could make it more difficult for President Barack Obama to win progress on that front before a global environmental summit in December.
Already facing a tough fight in the Senate and dwindling time before the summit to pass a bill, Democrats said they would not be able to unveil their legislation until "later in September."
Initially, the plan was to introduce a Senate bill to reduce emissions of carbon dioxide and other greenhouse gases blamed for global warming by around late July -- a timetable that had already slipped to early September before the latest delay.
Even so, Senate Majority Leader Harry Reid "fully expects the Senate to have ample time to consider this comprehensive clean energy and climate legislation before the end of the year," spokesman Jim Manley said.
Senate Environment and Public Works Committee Chairman Barbara Boxer and Senate Foreign Relations Committee Chairman John Kerry said in a statement they were making progress toward crafting a bill that Democrats will introduce.
More time was needed because of the struggle in Congress over healthcare legislation -- another of Obama's top priorities, which has been running into turbulence.
Boxer and Kerry also noted the death last week of Democratic Senator Edward Kennedy and hip surgery Kerry had this month, further complicating efforts.
With some moderate Democrats joining many Republicans in opposition to a climate change bill, Boxer and Kerry also could need more time to work out suitable language.
TWEAKING THE BILL
The House of Representatives narrowly passed a bill in June that would reduce U.S. carbon emissions by 17 percent by 2020, from 2005 levels. Boxer has said she would work off that bill, making "tweaks" to it.
Democrats are racing against a December deadline, when the United Nations is scheduled to hold a global summit in Copenhagen to discuss the next steps on controlling greenhouse gas emissions.
Obama badly wanted Congress to approve legislation by then as a way of demonstrating to the world the U.S. commitment to cutting pollution from coal-fired utilities and other industrial smokestacks.
Other large polluters, such as China and India, are closely watching Washington's response to the global environmental problem following years of little action.
The latest Senate delay also could take some of the steam out of a late September meeting of G20 countries -- large economies with a similarly large stake in world climate talks.
Some U.S. backers of climate change legislation were hoping that Boxer's Environment and Public Works Committee would have been able to approve a bill around the time of the G20 meeting in Pittsburgh.
"It would've helped out a lot" if the G20 could have convened as the Senate advanced a U.S. bill, said one international climate change expert. (Editing by Peter Cooney) (firstname.lastname@example.org; 202-898-8391; Reuters Messaging; email@example.com))