MP Michael Ignatieff announces his candidacy in the Liberal leadership race at a news conference in Ottawa on Thursday. (Tom Hanson/Canadian Press)

Liberal member of Parliament Michael Ignatieff formally entered the race for the leadership of the federal party Thursday, saying he's learned and changed since he first ran for the job two years ago.

"I'm running because I love my country and my party. I believe I can offer the leadership this country needs in tough times," said Ignatieff, 61, who held a news conference in Ottawa to make his bid official.

Two other candidates, Bob Rae, the former Ontario premier who was Ignatieff's university roommate, and New Brunswick MP Dominic LeBlanc have also announced their intentions to run a leadership campaign.

Ignatieff, who lost to outgoing Liberal Leader Stéphane Dion at the 2006 leadership convention, said his time as an MP has made him a better candidate, honed by long days in Parliament, going toe to toe with the prime minister.

"The country has changed, the party has changed, I've changed. I think I listen a little better, I think that I'm better known. I think I have been tested in the House of Commons four days a week," he said.

The former Harvard professor, who spent much of the past three decades living in the U.K. and U.S., said Canadians and Liberals have a better sense of who he is this time around.

"They know me. They see I don't have two horns and a tail."

Ignatieff, who acknowledged the recent federal election was tough on the party, said if he wins, there will be a wide-ranging Liberal policy conference 100 days after next year's leadership convention in Vancouver.

"This party needs to change. My objective in Vancouver is not simply to win, but to make this party stronger, more united, more convincing than ever," he said.

Many analysts have already labelled Ignatieff as the front-runner to succeed Dion, who announced he would be stepping down as leader after the party's poor showing in the Oct. 14 election. In one of the worst results in terms of popular vote for the party in more than 100 years, the Liberals took 77 seats. Going into the election, the party had held 95.

Ignatieff, a writer, journalist and academic, was first elected in the Toronto riding of Etobicoke-Lakeshore in 2006.

The leadership convention will be held in Vancouver from April 30 to May 3.

Rae welcomes entry

Rae, speaking on CBC Newsworld on Thursday, said he warmly welcomed his former university roommate's entry into the race.

"Everybody anticipated that Michael would run," he said. "I hope we'll have a lot of debates, for the people to hear the ideas, policies."

Critics believe Rae's conversion from the NDP to the Liberal party and his legacy as Ontario's premier as the biggest weaknesses of his bid for federal Liberal leadership. Rae held office from 1990 to 1995, a time marked by the province's worst economic downturn since the Depression, including record deficits and high unemployment.

Rae said his experience governing during tough economic times should be seen as a strength.

"We made some critical decisions as a province and I'm very proud of those. Did I learn some tough lessons in the course of it? Absolutely. But I think those lessons are very, very helpful," he said.

Both men have indicated they want the race to remain civil, without personal attacks.

Ignatieff, who told reporters he has a "sincere and deep and abiding" respect for Rae, said the race will boil down to different visions of the country's future.

"This isn't personal. This is strictly political," he said.

Expensive bid

Several other people who had been seen as potential contenders have said they will not be entering the contest. They include:

• David McGuinty.
• Gerard Kennedy.
• Denis Coderre.
• Martha Hall Findlay.
• John Manley.
• Frank McKenna.

Former cabinet minister Martin Cauchon and Brampton MP Ruby Dhalla are believed to still be weighing their options regarding whether they will run.

Rae said he believes the expense of gearing up for a run at the party leadership has narrowed the field of candidates.

"The party has chosen a very cumbersome [selection] process. It's costly, a big deal. To raise that kind of money is a challenge," he said.

Rae and Ignatieff have both paid off their debts from the last leadership contest. Dion still owes about $200,000.

Kennedy, a Toronto MP, who threw his support behind Dion during the last leadership conference, said he decided not to run for several reasons, including the fact that he has a young family.

"I'd rather direct my energies somewhere else right now," he told CBC News on Thursday, a day after he announced he wouldn't run.

Kennedy said rumours that he is supporting Ignatieff are "not true," and that he'll take time to decide who will best help the party.