Two Alberta MPs have declared their candidacy to become interim leader of the Conservative Party, making it at least a six-way race.

Rona Ambrose and fellow Edmonton MP Mike Lake will both be nominees when the 99-member caucus picks a successor to Stephen Harper at a meeting next Thursday.

Ambrose, who has held eight different cabinet posts since 2006, says she is well known for her civility in the House of Commons and believes a new, more respectful tone is what the party needs.

She says the interim leader will need to cultivate a higher profile in the media to compete with communications-savvy rival Justin Trudeau. She says her experience will help the party hold the new Liberal government to account.

"We must focus on challenging the Trudeau government by defending and promoting the conservative values and policies that so many Canadians embraced and voted in favour of," she said in a memo to her caucus colleagues.

"Our party needs to stand united and strong in the fight to ensure that taxpayer dollars are spent wisely and that government programs are managed effectively. The Liberals must be held accountable for their actions at every step."

Ambrose, who is bilingual, says she has the energy needed to travel across the country to rally volunteers and to fundraise — including in the province of Quebec — as the party prepares for the race for the permanent leadership and the next election.

The caucus will also need to vote on whether senators will be able to cast ballots for the interim leadership — and Ambrose says they should not be excluded.

Lake is entering his fourth term as MP, and had served as the Parliamentary Secretary to the Minister of Industry since 2008.

Other declared candidates in the race are Diane Finley, Rob Nicholson and Erin O'Toole from Ontario, and Candice Bergen from Manitoba.

With files from The Canadian Press