European leaders met on Thursday to forge energy policy to cut climate-warming gas emissions in the years to 2030, but haggled into the night over how to share out the costs of a deal.
The 28 member states want to set the pace for a global pact to be agreed in Paris next year with industrial powers from Asia, North America and the rest of the world.
That pact would aim to improve on two decades of stuttering cooperation and rein in carbon dioxide emissions blamed for a disruptive rise in temperatures.
As host of next year's United Nations summit to negotiate a global climate deal, French President Francois Hollande said Europe had to take the lead.
"If there isn't an agreement in Brussels among the countries that are furthest ahead on this issue, how are we going to convince the Chinese or the Americans or the poorer countries?" Hollande said on his arrival for the Brussels talks.
There is broad acceptance of an overall EU goal of cutting carbon emissions from homes, power plants, cars, planes, farms and other sources by 40 percent by 2030, compared with the global benchmark year of 1990.
The big stumbling block is how to share the financial burden of moving away from fossil fuel and investing in a greener energy mix.
After a series of bilateral talks before all 28 member states sat down to discussions around 2100 GMT, diplomats said a deal was within reach and that nations, such as coal-dependent Poland, were being offered help with shouldering the cost.
Poland - whose new prime minister Ewa Kopacz is attending her first EU summit - fears the political fallout from policy that could shut coal mines a year before an election.
The nation has long led objections to EU efforts to be more ambitious about curbing emissions, but other nations have also raised concerns about the proposed deal.
British counterpart David Cameron says too much red tape will fuel Eurosceptic demands to quit the EU.
Portugal and Spain, meanwhile, which are keen to export energy, pressed for stricter targets and incentives to push France to accept more power connections being built to link Iberia across the Pyrenees.
BUILDING ON 2020
The plan is to build on existing green policy goals to 2020, which have greatly increased the amount of renewable energy used and cut overall energy use through measures such as increased building insulation and more fuel-efficient cars.
At the same time, EU carbon emissions have already fallen to nearly 20 percent below 1990 levels, helped by the collapse of polluting industries in eastern states after the fall of communism 25 years ago.
For 2030, the European Commission, the EU executive, has laid out three targets: as well as cutting emissions by 40 percent from 1990, the executive proposes green fuel should provide at least 27 percent of energy with energy efficiency improved to 30 percent compared with business as usual.
Any deal agreed this week will commit governments in principle for years to come, but detailed law will only be worked out later and could take account of how far other global powers follow suit.
While some in industry have warned new climate goals will drive them out of Europe, Green campaigners say the European Union is being nowhere near ambitious enough, especially when the conflict between Ukraine and Russia, the bloc's main energy supplier, has heightened the need to reduce reliance on imported fossil fuel.
"We have a very clear signal to accelerate efforts and we are slowing down. Even forgetting the climate, it's a colossal error. There is a lot of short-term reasoning," Philippe Lamberts, co-chairman of the Greens in the European Parliament, said on the sidelines of the summit.
