"There has occasionally been voiced the misimpression that a future administration will take a significantly different attitude towards climate than this administration," said deputy national security adviser Dan Price.
"It would be a political miscalculation were some countries to believe that a future administration or a future congress will be less concerned about addressing comprehensively the question of emissions from all major economies," said Price, whose brief is international economic affairs.
The presumptive nominees to succeed Bush -- Democrat Barack Obama and Republican John McCain -- have said publicly that they plan to take a different approach from Bush's strategy, which has drawn fire even from US allies.
Price's comments came as the US president prepared to leave Washington Monday for the US-European Union summit in Slovenia, followed by stops in Germany, Italy, the Vatican, France, and Britain.
"We have tried to explain that it is highly unlikely that any future administration would be prepared to sign a new climate treaty that did not include binding commitments from the major emerging economies to address their own emissions," Price told reporters in a pre-trip briefing.
He had been asked whether even US allies were giving signs that they were prepared to wait out Bush's term, which ends in January, to pursue global free trade talks and climate change matters.
"On trade, I am not hearing that. In fact, what I am hearing is the desire of major WTO (World Trade Organization) members to try and reach agreement with this administration knowing of its commitment to trade liberalization, and to try and get that done this year," said Price.
"The concerns that have been expressed about US trade policy have been concerns about what they may hear from the campaign trail, or what they may hear in connection with the handling of our bilateral free trade agreements," he said.
"But I've heard nothing to suggest that our trading partners do not wish to conclude the WTO agreement with us this year," he said.