Michael Ignatieff speaks with the media Wednesday during a news conference in Ottawa. (Sean Kilpatrick/Canadian Press)

Interim Liberal Leader Michael Ignatieff said Wednesday he's prepared to vote out the Conservatives and enter into a governing coalition with the NDP if next month's federal budget isn't in the country's best interest.

"I told caucus I will vote non-confidence in this government. I am prepared to enter into a coalition government if that is what the Governor General asks me to do," he said during an Ottawa news conference shortly after the Liberal party's national executive appointed him to replace Stéphane Dion.

"I also made it clear to the caucus, no party can have the confidence of the country if it decides to vote against a budget it hasn't even read."

The coalition, formed in protest over the Tories' fall economic update, was set to topple the Conservatives in a no-confidence vote scheduled for last Monday and form a new government, with Dion as prime minister and members of the NDP in cabinet, with the support of the Bloc Québécois on all confidence motions.

But the Tories avoided the vote after Gov. Gen. Michaëlle Jean agreed to grant Prime Minister Stephen Harper's request to suspend Parliament until late January, when the Tories will table a budget.

Ignatieff, who was largely silent in the days following the formation of the coalition, blamed Harper for unleashing a "parliamentary crisis" by failing to address the economic slowdown in the fall update.

He said the Liberals will make known in the coming weeks the measures they believe should be in the Jan. 27 budget, but added it is up to Harper to make the first move.

"I'm not entering into negotiations with Harper. He knows where he can find me," said Ignatieff. "If he needs any help … we might oblige."

Later in the afternoon, word emerged that Harper and Ignatieff were to speak by phone Wednesday evening.

Ignatieff said the prime minister must open up the country's books when he and Liberal finance critic Scott Brison attend a pre-arranged meeting with Finance Minister Jim Flaherty next week.

"We believe Mr. Harper and Mr. Flaherty did not tell … Canadians the truth about the state of the Canadian economy," said Ignatieff. "Unless we start getting the numbers, getting the truth, as a common baseline, we’ve got nothing to talk about."

Olive branch from PM?

Ignatieff also warned the prime minister against governing as if he has a majority in the House of Commons.

"You cannot run a minority Parliament with divisive, spiteful and unproductive policies we saw in that autumn statement. He's got to walk back down the hill," he said. "If he does, my party has never failed to exercise leadership in the national interest."

In an interview with the CBC's Peter Mansbridge on Tuesday, Harper urged the "big national parties" to work together, suggesting that he, too, was looking forward to a better relationship with the Liberals under Dion's replacement.

"I hope the next Liberal leader, the first thing he'll do will be … to sit down with me and have that kind of discussion."

While Harper appeared to extend an olive branch, the Conservative party on Wednesday issued a fundraising letter painting Ignatieff as a parachute leader with no elected legitimacy even within Liberal ranks.

Rae nominated Ignatieff

The Liberal party's national executive named Ignatieff interim leader Wednesday afternoon after phone consultations with about 800 party members. Liberal senators and MPs unanimously endorsed Ignatieff earlier in the day during a caucus meeting.

The appointment came a day after Ignatieff's remaining leadership rival, Toronto MP Bob Rae, withdrew from the leadership race.

Rae, a former NDP premier of Ontario, nominated his former college roommate during Wednesday's caucus meeting. Former leadership contender and New Brunswick MP Dominic LeBlanc seconded the nomination.

"We really have left this caucus meeting feeling united, recognizing that we can now focus on the issues at hand. We are facing in an economic crisis. And we have a prime minister who ran away from government," Toronto MP Martha Hall Findlay said after emerging from the meeting.

Hall Findlay said Dion also spoke at the meeting and said "all the right things."

Dion moved up his departure date, originally scheduled for May when the party was to pick his replacement at a leadership convention.

"I'm very proud to leave in a way to give Canadians a great leader with Michael Ignatieff," said Dion on his way out of Wednesday's caucus meeting, crowded by a throng of reporters.

Ignatieff, who as the leadership race began had the support of the majority of the caucus, is expected to be formally acclaimed as permanent leader at the party's convention from April 30 to May 3.

It's unclear if anyone else would contest for the leadership. Under the party executive's constitution, a convention must be held to choose a permanent leader.

Quebec reviews good

Liberals in Quebec say Ignatieff's new role will bode well with party members in the province, who largely rejected Dion. The Liberals managed to win only 13 seats in the October election.

William Hogg, who ran as a Liberal candidate in the Eastern Townships, said Ignatieff, a Toronto MP, is popular among francophones.

"He [offers] a very strong package with francophone Quebec. He also has roots in the Eastern Townships," said Hogg, who teaches political science at Bishop's University in Sherbrooke.

"He was also very significant in 2006 promoting the opening of the party to francophone Quebec with that whole Quebec nation resolution process."

Ignatieff was alone among the 2006 Liberal leadership candidates in proposing the idea of granting Quebec "nation" status.