Canada's governing Conservative party has defeated a climate change bill calling for cuts in the country's CO2 emissions.
Conservatives in the Canadian senate killed the motion, which was backed by opposition parties, in a vote on Tuesday.
Prime Minister Stephen Harper claims the country, which is the world's tenth-largest emitter of CO2, needs to wait for the United States to act, so that the two neighbours can harmonise their environmental policies.
Opponents have called the approach a stalling tactic.
The defeat comes just 13 days before a UN climate change summit in Cancun, Mexico.
The bill, which called for a reduction of 25 per cent in the country's greenhouse gas emissions compared to 1990 levels, was originally passed by Canada's House of Commons last year.
The Conservative Party's opposition to the bill was welcomed by US ambassador to Canada, David Jacobson, in a speech at Montreal's McGill University on Tuesday.
"The practical reality is that in Canada you can't have a system of carbon pricing that is different from the one in the United States," Jacobson said Tuesday during a speech.
"The negative effects on trade, on business and on environmental stewardship, in one country or the other, would be very significant."
Opposition heads condemned the defeat, Democratic Party leader Jack Layton calling it: "A very sad day for Canada, for the environment, and for the role of Canada in the international stage on dealing with the crisis of climate change".
US federal policy on the environment has lagged behind that of a few key states such as California, which earlier this month voted not to suspend a law committing the state to reductions in CO2 in accordance with the international Kyoto protocol.
Canada's Conservatives say they hope to reduce greenhouse gases in the country by 20 per cent compared to 2006 levels by 2020 - a tiny gesture compared to the European Union's commitment to cutting emissions by up to 30 per cent on 1990 levels in the same time frame.