Prime Minister Stephen Harper unveiled a newly expanded cabinet Thursday, moving Rona Ambrose out of her environment portfolio as he tries to recover political ground lost in the debate on climate change.

In all, five new junior cabinet positions were created and eight ministers took on new roles or switched posts as Harper moved to overhaul his minority government with the threat of a looming spring election.

"Over the past year, we have been delivering change by getting things done for families and taxpayers," Harper said in a written statement.

"Our new ministerial team will continue to deliver on the government's commitments to Canadians."

Ambrose is taking on the intergovernmental affairs post, a role that she has experience in from her days working in the Alberta government. Ambrose will also serve as minister of western economic diversification.

Meanwhile, John Baird leaves his post with the Treasury Board to take over the increasingly important environment portfolio.

Baird is known for his spirited attacks on the opposition during parliamentary debates and takes credit for successfully shepherded the Federal Accountability Act through the parliamentary process.

Ambrose's future as environment minister was cast into doubt after she was lambasted by opposition members and environmentalists for her handling of the key portfolio -- specifically the way she sold the government's proposed Clean Air Act.

Reacting to Harper's cabinet shuffle, Liberal Leader Stephan Dion called the Conservative environmental policy an embarrassment to Canada which cannot be solved simply by shifting players.

But Harper claimed Ambrose accomplished more in one year than the previous Liberal government did in 13 years. However, he conceded work on the environment was far from complete.

"We've clearly determined that we need to do more on the environment,'' he told a news conference.

"We recognize that, particularly when it comes to clean air and climate change, that Canadians expect a lot more.''

In other significant changes, Robert Nicholson moves from government House leader to justice minister; Monte Solberg gives up the immigration portfolio to become human resources minister; Vic Toews leaves his justice post to become Treasury Board president; and Diane Finley has become immigration minister.

Ontarian Peter Van Loan has become House leader while Senator Marjory LeBreton has taken on the additional responsibility of secretary of state for seniors.

"In recognition of the growing importance of senior citizens in our country, I believe it is important to have an advocate, like Marjory LeBreton, to ensure that we are doing what we need to for those who have contributed to making Canada such a vital and strong country," Harper said in a written statement.

Five MPs were sworn in as new junior ministers:

• Alberta's Jason Kenney as secretary of state for multiculturalism and Canadian identity
• Ontario's Helena Guergis for secretary of state for foreign affairs and international trade
• Saskatchewan MP Gerry Ritz for secretary of state for small business and tourism
• Quebec City's Christian Paradis for secretary of state for agriculture
• British Columbia's Jay Hill takes on a general role of secretary of state

Sources told The Canadian Press that Harper consulted heavily with Conservative campaign director Doug Finley -- husband of Diane Finley -- on what would be the best makeup of cabinet ahead of another election.

"You find when you make one or two changes you find, by necessity you must make others. ... we felt we had to make some changes to make sure we had the people in the portfolios that were most suited to them," Harper said.

The departure of Ambrose from the environment portfolio leaves the Conservative cabinet vulnerable to accusations of weak female representation.

Where there were six women on the 27-member cabinet there are now seven of 32. Critics say none of the current group hold prominent positions.

But Harper abstained from admitting the new cabinet was designed to sell Canadians on his party in advance of the next election.

"I wouldn't call it an election cabinet because I am not planning to call an election -- and who knows, there could be other changes if an election took place."

Harper said the government is working on a new budget that will cut taxes, focus spending, crack down on crime, improve democratic institutions, boost Canada's profile on the world stage and address the so-called fiscal imbalance with the provinces.

"Make no mistake,'' he said."We are determined to drive this agenda to a conclusion.''

Harper's Conservatives will face a key test when they deliver their next budget, defeat of the fiscal agenda would automatically trigger a new election.

The environment file has been widely seen as the Harper government's biggest challenge and is bound to become an election issue.

A source told The Canadian Press Ambrose had been getting advice on the side from former prime minister Brian Mulroney and one of his former cabinet ministers Barbara McDougall.

Mulroney warned last month that unless Harper moves quickly on the issue, other parties -- including the Liberals under Stephane Dion, who campaigned for the Grit leadership as champion of the environment -- could claim the issue.

Given the Liberals' record on the environment, added Mulroney, that scenario would be a tragedy.