Deputy Liberal Leader Michael Ignatieff says he supports party Leader Stephane Dion and urges his fellow Liberals to stay united.

"We need discipline. We need unity. United parties win, and divided parties lose," he told CTV's Question Period on Sunday in his first national interview since March.

Dion's leadership hit a rough patch since the party did poorly in three Quebec federal byelections last month.

The Liberals lost their long-time Montreal stronghold of Outremont to star NDP candidate Thomas Mulcair, a former provincial Liberal environment minister.

Ignatieff bristled at suggestions the Liberal party could be starting to slowly slide into irrelevancy and that the NDP could eventually supplant them.

He called suggestions of irrelevancy "ridiculous" and an insult to the "millions of people who voted for us.

"A third of this country wants to vote for the Liberal party if you give it half a decent reason to do so," he said.

"We have an electoral base that (NDP Leader) Jack Layton can't even begin to think about ... Don't ever underestimate the Liberal party -- that's all I'm saying."

In the latest Harris-Decima poll the Liberals were at 31 per cent support nationally, compared to 33 per cent for the governing Conservatives and 16 per cent for the NDP.

While Ignatieff called for party unity, some of those calling for the dismissal of national director Jamie Carroll -- a Dion loyalist accused of downplaying the need to have more Quebecers in Dion's inner circle -- are people  linked to Ignatieff's leadership campaign.

"Let's take the labels off our necks here," Ignatieff said. "There are no more Ignatieff people, Dion people, Dryden people, Brison people. They are Liberals. And we have to fight and win as a team, and we will."

Ignatieff noted  that within 30 seconds of losing to Dion at last December's leadership convention, he   pledged support to the new leader. "I pledged my support then. It remains now," he said.

While saying he and Dion spoke all the time, when asked about the state of the relationship, Ignatieff said, "The thing about any relationship is the more you say about it, the less effective it is."

Another top Liberal leadership hopeful -- Bob Rae, who finished third -- recently wrote in The Globe and Mail that Conservative proposals to limit federal spending power would emasculate the federal government.

"The Liberal party, since Laurier, has believed in a strong federal government," Ignatieff said.

"We've also been a party, and Mr. Dion was part of this, that's respected the competences of provinces."

If Prime Minister Stephen Harper drastically weakens the federal government, "that's a serious issue to all Canadians," he said.

A strong federal government helps preserve national unity, he said.

Throne speech

Parliament resumes on Oct. 16 with a new throne speech.

This past week, Prime Minister Stephen Harper said in a rare news conference that the opposition must  support his legislative agenda if it supported the throne speech.

Voting down the throne speech would be an expression of non-confidence in the government, and an election could be triggered. But Harper went even further, saying most bills would be considered votes of confidence in the government.

"If Mr. Harper was prepared to make a minority parliament work, it would be easy," Ignatieff said, noting the Liberals were prepared to fast-track a large number of Conservative criminal justice bills in the last session.

"If this man respected compromise and respected Parliament, he could make Parliament work. I think the prime minister has made a decision he doesn't want Parliament to work. I think we have to face that reality."

Ignatieff said the Liberals won't make a decision on the throne speech until they've actually seen the document.

"If the government proposes a moderate, sensible speech that's in the national interest, that's one thing. If it's one, long poison pill, that's another."

Ignatieff said he thinks there's a lot of election fatigue right now, given the number of provincial campaigns, "and a responsible opposition has to keep that in mind."