WASHINGTON  The United States will propose a near-term target for reducing greenhouse gas emissions before the United Nations climate change meeting in Copenhagen next month, a senior administration official said Monday. President Obama, the official said, will announce the specific target “in coming days.”

The announcement of a target will take the current legislative stalemate over a climate bill into account, the senior official said, and thus might present a range of possible reductions rather than a single figure.

The lack of consensus in Congress puts Mr. Obama in a tricky domestic and diplomatic bind. He cannot promise more than Congress may eventually deliver when it takes up climate change legislation next year. But if he does not offer some concrete pledge, the United States will bear the brunt of the blame for the lack of an international agreement.

The official also said the president would decide shortly whether and for how long he might attend the December climate meeting, which runs from Dec. 7 to Dec. 18. He repeated the president’s assertion that he would consider attending if his presence could be a useful impetus to a deal.