Conservative leadership candidates Peter MacKay, Erin O'Toole and Marilyn Gladu all say that if they're chosen to lead the party, they'll try to topple the Liberal government as early as possible.

In a fundraising email sent out to party members today, MacKay says that, under his leadership, the Conservative caucus would "bring a motion of non-confidence to the House of Commons. We will defeat the minority Liberal government as soon as possible.

"We need an election in October."

Responding to MacKay's message today, O'Toole issued a statement saying Prime Minister Justin Trudeau's "failure to lead is causing serious damage to Canada. As soon as I become leader, I will table of motion of no confidence in the government."

Another candidate, Ontario MP Marilyn Gladu, beat both MacKay and O'Toole to the punch.

In Facebook post on February 24, Gladu said that, if she's elected Conservative leader, her "first act will be to call on other opposition parties to join with us to bring down this government and allow Canadians to elect a government that will work in their best interests."

The Conservatives don't have the votes in the House of Commons to bring down the government on their own. They'd have to secure support from the Bloc Québécois and NDP caucuses.

This afternoon, NDP Leader Jagmeet Singh suggested the Conservatives can't rely on New Democrats to help them bring down the government.

"We know this about Conservatives: they make hurtful cuts to public services and help the wealthiest and well-connected corporations," Singh said in a media statement. "That's their priority with whoever becomes the next leader of the CPC. They haven't learned that this isn't about sending Canadians back to an election, but rather getting things done to help make their lives better.

"In the last election, Canadians were clear: they wanted parties to work together to get things done for them. If the Liberals want to get things done for people, they can work with us to deliver. If they don't, they can't count on our support."

In his letter, MacKay cites the recent rail protests and subsequent layoffs as reasons to bring down the Trudeau government early.

"With a strong and united party, we can win the election and form a strong and united government," the letter says.

MacKay is widely seen as the leading candidate in the race to replace current leader Andrew Scheer.

On Saturday, the party issued the final list of eight candidates who have met the initial conditions to run.

The results of the leadership race will be announced June 27 in Toronto.