President Zarkozy's speech was welcomed by developing nations
French President Nicolas Sarkozy has backed calls by developing nations to keep the Kyoto Protocol, which only requires rich nations to cut emissions.
Speaking in Copenhagen, he broke away from the EU position of favouring a new deal that saw all nations commit to measures to curb climate change.
Elsewhere, the US and China have been at loggerheads over binding targets.
With one day remaining, observers say the climate summit is unlikely to deliver a meaningful deal.
The Danish presidency of the climate summit in Copenhagen has sought to play down expectations of a comprehensive deal emerging from the meeting.
Richard Black, BBC News environment correspondent
The shape of a possible political deal has emerged here during a day of private ministerial meetings.
It appears that the Danes have been relieved of political leadership behind the scenes, with Gordon Brown and Kevin Rudd - with input direct from the Washington White House - steering moves to induce all the "important" parties to buy in.
Leaders would have some big decisions to make, however, probably including a target for limiting temperature rise, long-term funding for developing countrues, and verification of emission cuts.
Some small developing countries are not entirely happy but the big players appear to be more confident than they were this morning of bringing everyone on board.
The hosts had to drop plans to propose new draft texts on Thursday after opposition from many developing nations, which saw the talks grind to a halt on Wednesday.
Officials said progress could be made, but an international agreement may have to wait until a 2010 meeting in Mexico.
In his address to delegates, Mr Nicolas Sarkozy called on nations to "stop posturing".
"A failure in Copenhagen would be a catastrophe for each and everyone of us," he said. "If we keep on heading where we're going, we are heading for failure."
"So people want to keep Kyoto, OK let's keep Kyoto. But let us agree on an overall political umbrella," he stated.
The French president went on to urge ministers and leaders to adopt a full climate treaty in June 2010.
"Let's give ourselves six months after the Copenhagen conference to transform political commitments into a legal text."
Money on offer
Eariler, US Secretary of State Hillary Clinton told the meeting her country was prepared to work towards mobilising $100bn a year for developing countries.
She told delegates: "In the context of a strong accord in which all major economies pledge meaningful mitigation actions and provide full transparency as to those actions, the US is prepared to work with other countries towards a goal of mobilising $100bn a year to address the needs of developing countries."
She made it clear - as did Japan on Wednesday when announcing a specific figure for assistance - that the money was contingent on reaching a global deal here that met its criteria.
COPENHAGEN CLIMATE SUMMIT
Delegates from 193 nations are in Copenhagen to negotiate an agreement on curbing greenhouse gas emissions, in order to prevent dangerous climate change
Developing nations want rich nations to cut emissions by at least 25% by 2020 - rich nations are reluctant to go so far and want developing countries to curb emissions too
The US will not accept legally binding emissions cuts unless China does the same. China is unlikely to allow international scrutiny of its emission cuts
Ongoing disagreement on how funds to mitigate and adapt to climate change will be provided. Poor nations want direct aid, while the West favours schemes like carbon trading
BBC environment correspondent Richard Black said developing countries are likely to point out that there is no figure for what the US is prepared to provide itself, either from public or private finance.
The sum is also less than the amount that UN agencies such as the World Bank and International Energy Agency calculates is necessary to help mitigation and adaptation in the developing world.
But transparency has emerged as a major sticking point for the US. It has been calling on some developing countries, including China and India, to open their emissions controls to international scrutiny.
White House spokesman Robert Gibbs said China had to give ground on the US demand for transparency.
China says it is willing to provide information about its measures to reduce emissions, reports the AP news agency.
Vice Foreign Minister He Yafei is quoted as saying that China is ready for "dialogue and co-operation that is not intrusive, that does not infringe on China's sovereignty".
Addressing the summit on Thursday, Australian Prime Minister Kevin Rudd said he feared "a triumph of form over substance" at the outcome of the UN climate summit.
In his speech, UK Prime Minister Gordon Brown, meanwhile, urged the summit to "summon up the greatest level of ambition".
"The success of our endeavours depends on us forging a new alliance," he told delegates.
He added: "In these few days in Copenhagen which will be blessed or blamed for generations to come, we cannot permit the politics of narrow self-interest to prevent a policy for human survival."
Yvo de Boer, executive secretary of the UN's climate body, told reporters that negotiators would consider two negotiating texts; one looking at further emission cuts by developed nations (except the US) by 2020, and another that looks at committing all nations to curbing climate change.
Mr de Boer added that the texts would be considered by two working groups, which were expected to report back to the main conference on Thursday evening.
Saleemul Huq, senior fellow in climate change at the International Institute for Environment and Development, told BBC News: "The negotiation process is in a high state of confusion."
"On the other hand, heads of state are arriving and talking to each other, and within hours every important decision-maker on the planet will be in the same town at the same time.
"If they can't do it, no-one can - and I think that they will."
India's environment minister Jairam Ramesh said a "blame game" had already begun because of the slow progress towards a deal.
Containing emissions to a level associated with a temperature rise of no more than 2C is the stated aim of the big nations here.
As things are going they will miss that target by a considerable margin, our correspondent says.
The poorest and most vulnerable nations say emissions should be contained to a level associated with a temperature rise of 1 or 1.5C.
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