Liberal Leader Justin Trudeau said Thursday that his former campaign co-chair Dan Gagnier's letter to a number of people pushing for the Energy East pipeline to be built was "inappropriate," and that Gagnier has decided to step down from Trudeau's team for the "long-term future."

Trudeau said that due to his connections to people in the energy industry, Gagnier was never involved in shaping Liberal energy policy but rather held an advisory role, and his voluntary resignation showed accountability.

"We are well aware of the challenge of perceptions in politics and of the challenges the Liberal party has had to address in the past," Trudeau said.

"That's why we took immediate action to say that this action was unacceptable, inappropriate and Mr. Gagnier fully assumes the responsibility for his actions and stepped down."

The Liberal leader also said that if his party forms government after the Oct. 19 vote, it would set a higher ethical standard.

It was revealed Wednesday that Gagnier had sent a detailed letter to five TransCanada Corp. officials behind the Energy East pipeline, outlining how they could best lobby a government — including a Liberal government — to have the pipeline approved.

Trudeau's campaign initially stood behind Gagnier, saying he did not break any laws or ethical standards, and went as far as to blame the Conservative campaign for stirring up a controversy where none existed.

By afternoon, however, Gagnier resigned from the campaign, saying he didn't want to be a distraction.

"I deeply regret that the campaign has been affected by these negative, personal attacks," his statement read. "I have always conducted my business openly and in full accordance with the rules. In the best interests of the party, I have taken this decision. I continue to support Justin Trudeau and hope for a Liberal government on Oct. 19."

Dan Gagnier's work as a lobbying consultant for TransCanada Corp. was known publicly for months, Justin Trudeau said Friday. (liberal.ca)

This morning during a campaign stop in Montreal, however, Trudeau said Gagnier's letter was "inappropriate" and that the Liberals remain committed to the highest ethical standards possible. As a result, the Trudeau campaign decided to support Gagnier's decision to step down as a national co-chair.

"Mr. Gagnier has a long history of working with governments and has always behaved in a responsible way," Trudeau said.

"He acted in an inappropriate way a few days ago and when we found out about it, we sat down with him and he chose to do the responsible thing and step down from our campaign. It's a way of demonstrating the fact that we take ethical standards and responsibilities extremely seriously."

Trudeau asked what national campaign co-chair's resignation says about the Liberal Party's ethics 1:15

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Gagnier will remain away from his team "for the long-term future," Trudeau said.

Trudeau also said the Harper government has always used the excuse that "no rules were broken" to justify ethically indefensible behaviour.

Former Liberal prime minister Jean Chétrien, who was out campaigning with a Quebec Liberal candidate Thursday afternoon, said since Gagnier resigned the discussion should move on to issues about the future of the country.

"He sent an email to some clients and he resigned. Was it wrong? I don't want to debate that because he resigned. Let's talk about the future. He's not there anymore. Next?" Chrétien said to the crowd.

Former prime minister Jean Chrétien wants to look to the future following the resignation of Liberal campaign co-chair Dan Gagnier amidst controversy. 0:52

But during a campaign event Thursday in Trois-Rivières, Que., Conservative Leader Stephen Harper said Gagnier's actions smacked of a Jean Chrétien-era scandal that helped bring Harper to power a decade ago.

"I believe the culture of the Liberal party that gave us the sponsorship scandal has not changed," Harper said.

'They are all about helping themselves'

During a campaign stop in Quebec, NDP Leader Tom Mulcair also pulled no punches when discussing the Liberals' recent problems.

He said Gagnier's letter and later resignation are evidence that "although they tried to put on a fresh face, this is the same old Liberal Party, the same old gang and the same old tactics and strategies."

"You can't trust the Liberals. It's the same old Liberal Party," he said.

"They are all about helping themselves ... It's an extraordinary opportunity for everyone in Canada, including those here in Quebec, that this is the same old Liberal Party of the sponsorship scandal," Mulcair said to a crowd of supporters. He added that Canadians finally have an opportunity to elect a party that has not been rocked by scandal.