President George W Bush is under pressure from European allies to give ground on climate change at next week's meeting of the world's richest countries, but policy experts say prospects for a breakthrough are slim.
The sticking point is Bush's longstanding opposition to measurable goals for reducing emissions of the greenhouse gases that spur global warming.
Bush enjoys a strong rapport with German Chancellor Angela Merkel, who is hosting the Group of Eight summit in the Baltic resort of Heiligendamm on June 6-8 and has made fighting climate change the top issue at the summit.
Combating global warming is also a concern for new French President Nicolas Sarkozy, with whom Bush wants to forge a good relationship, and for outgoing British Prime Minister Tony Blair, a close friend to Bush and an ally in the Iraq war.
As negotiators try to hammer out the final language in a communique, the United States has blocked an emerging consensus in favour of firm targets. It is unclear whether a last-minute compromise can be reached.
"I think that there is considerable pressure coming from the Europeans for some type of American concessions on the issue of climate change," said Charles Kupchan, professor of international relations at Georgetown University.
"Setting aside Iraq, if there is one issue that creates resentment, it is the sense that the United States is contributing callously, more than any other country, to global warming," Kupchan said.
White House spokesman Tony Snow said he expected the United States to play a leadership role and emphasized initiatives Bush has already unveiled, including his goal of reducing US gasoline consumption by 20 percent over the next decade.
'Odd man out'
Acknowledging that climate change exists and must be addressed, Snow told reporters, "We believe the most effective way is to go aggressively after technologies that are going to mitigate the problem."
Grant Aldonas, former undersecretary for international trade at the US Commerce Department and now with the Center for Strategic and International Studies, said Bush is likely to urge building on earlier initiatives, such as encouraging the development of biofuels and energy-efficient technology.
Washington is seen as the summit's "odd man out" on global warming, but Aldonas said Bush is used to that: "I don't think at this stage, having taken the sort of opprobrium of the international community over Kyoto, that the president is going agree to numerical targets at all."
The Kyoto Protocol is an international pact to cut climate warming emissions, which the Bush administration rejects as a threat to the US economy.
But there has been a clear rhetorical shift at the White House which now acknowledges that climate change is a concern.
Meeting this month with Britain's Blair, Bush went out of his way to mention that they spent "a lot of time" discussing climate change. He said the United States wanted to help solve what he called a serious issue.
"I think the president actually has been convinced by the science," Aldonas said. He and other analysts said Bush is now facing new domestic pressures to act on climate change.
Annie Petsonk, international counsel for the green group Environmental Defense said G8 negotiators were emerging from a "fog of diplomacy" to realise that the White House position on climate change was not necessarily shared by Congress, the US courts or the American people.
"The fact that Congress is now moving ahead to consider cap and trade legislation (to curb climate-warming emissions) and the US states ... have taken the lead on this issue, they are showing the rest of the world that there is more to America's position on global warming than the administration's 'Just say no' approach," Petsonk said.