A Conservative senator who helped defeat a climate-change bill says the vote was not orchestrated by the government, but rather was the result of a Liberal mistake.

Senator Marjory LeBreton, the government leader in the Red Chamber, said Tuesday's vote occurred after Tory senators tried to stand the bill, meaning they wanted to leave it on the Senate schedule until they were ready to debate the legislation.

However, LeBreton said Sen. Grant Mitchell did not want to stand the bill -- a move that actually forced a vote on the bill's second reading.

"We were as surprised as anyone else that the Liberals forced a vote on second reading of this bill," LeBreton told CTV's Power Play.

"But once the Liberals presented us with an opportunity to defeat the bill, we of course were going to take it and defeat the bill because the government does not support this bill. The fact of the matter is this was not part of a strategy, this was something that landed in our laps. It was an opportunity to defeat the bill and we took the opportunity."

The surprise vote killed the Climate Change Accountability Act by a tally of 43-32. A number of Liberals were not in the Senate when the vote occurred.

LeBreton was responding to questions about accusations levelled by NDP Leader Jack Layton, who accused the prime minister of ordering Conservative senators to kill the legislation.

"Harper has lost his moral centre," Layton told Power Play, echoing comments he made earlier during question period in the House of Commons. "He stacked more into the Senate than any prime minister has ever done and then he turns around and uses those senators to overturn a decision of the democratic elected representatives of Canada on a vital issue."

The Climate Change Accountability Act, which was introduced by the NDP, called for greenhouse gas emissions to be cut 25 per cent below 1990 levels by 2020. The Harper government has set a cut of 17 per cent from 2005 levels by 2020, a target that is in line with that of U.S. President Barack Obama.

MPs passed the bill in May, when it went to the Senate.

When faced with Layton's accusations during question period, Harper said the Tories have been "very consistent and very clear" in their opposition to the bill, which he called "completely irresponsible."

"(The bill) doesn't lay out any measure of achieving (targets) other than by shutting down sections of the Canadian economy and throwing hundreds of thousands and possibly millions of people out of work," Harper said. "Of course we will never support such legislation."

LeBreton said despite the lack of government support for the legislation, Tory senators were prepared to continue discussing the bill and send it back to committee for further review.

Earlier Wednesday, environmentalists decried the results of the vote, saying the government is now headed into the upcoming United Nations climate talks in Cancun, Mexico, without a climate-change plan.

Representatives from 200 countries are scheduled to meet later this month to try to hammer out an international deal.

"As we head into the UN climate talks in Cancun later this month, it is unacceptable that Canada's only climate-change legislation has been defeated after years of majority support from our elected members of Parliament and their constituents," Graham Saul of the Climate Action Network Canada said in a statement.

Environment Minister John Baird denied Wednesday that the government doesn't have a climate-change plan heading into the Cancun conference.

Baird told Power play the targets set in the defeated climate bill were "unachievable."

But he said Canada will stick with its 17 per cent emission reduction target, and continue to work extensively with the Obama administration on environmental issues.

"Canada has a plan to eventually phase out our dirty coal power electricity generating stations," Baird told Power Play. "We are not perfect by any stretch but we are making good progress."

With files from The Canadian Press