UPDATE 2-Obama's drive for climate change bill hits delay

* Work slows in leading Senate panel writing bill

* Senior Republican says doubts vote this year

(Recasts lead, adds quotes and details)

By Richard Cowan

WASHINGTON, July 9 (Reuters) - As President Barack Obama encouraged world leaders meeting in Italy to intensify the fight against global warming, legislation to cut U.S. emissions of greenhouse gases suffered a delay in the Senate on Thursday.

The leading Senate committee responsible for developing the climate change legislation has delayed by at least a month its crafting of a bill, leaving less time for Congress to fulfill Obama's desire to enact a law this year.

"We'll do it as soon as we get back" in September from a month-long break, Senate Environment and Public Works Committee Chairman Barbara Boxer announced.

Earlier this week, Boxer, a Democrat, said her committee had planned to complete work on a bill by early August.

A White House spokesman, who asked not to be identified, said, "The administration is continuing to work with the Senate to pass comprehensive energy legislation and believes it's on track." He would not discuss timetables, though.