Hedegaard will soon embark on a climate diplomacy tour to reinvigorate global negotiations after the weak outcome of talks in Copenhagen in December.
The UN talks hammered out the so-called 'Copenhagen Accord' to limit global temperature rises to within two degrees Celsius of pre-industrial temperatures, but had little legal clout and no combined vision for cutting climate-warming emissions.
Experts say the emission cuts pledged alongside the accord set the world on track for a 3.5 degree temperature rise.
European Commission President José Manuel Barroso told EU leaders in a letter that the bloc needed a fresh approach to international climate politics and had to find new ways to instil trust back into the process.
"This is not the time for the EU to start doubting its commitments," he wrote. "We need the international process to continue, building on what we could agree in the Copenhagen Accord."
"I have therefore asked Connie Hedegaard, the commissioner for climate action, to undertake a consultation of key international partners to find ways to reinvigorate the international process," he added.
Hedegaard will visit a number of key capitals in her search for alliances with Africa, China, Brazil, the United States and others, said a spokesman.
Barroso also urged European leaders not to forget their promise to urgently channel 7.3 billion euros ($9.9 billion) in "climate aid" to poor countries to help them cut industrial emissions and tackle climate impacts on crops.
EU leaders agreed in December to hand out 2.43 billion euros a year from 2010-2012 to plug the gap until a global deal is struck for the years after 2013. But the Copenhagen talks failed to define channels to distribute that money.
"An important element in this strategy should be the implementation of the fast-start financing," Barroso wrote.
"We should not forget that those who were working more closely with us in Copenhagen were the developing countries, particularly the poorest and most vulnerable."
As for finding a successor to De Boer, UN Secretary-General Ban Ki-moon will decide in the coming months on a replacement to head the Bonn-based secretariat of the UN Framework Convention on Climate Change (UNFCCC).
De Boer said "it remains to be seen" if the next annual meeting in Mexico in November and December would agree a full treaty. He said there seemed to be support for an extra set of UN talks in April, perhaps in Germany or France.
(EurActiv with Reuters.)