Stephen Harper has "turned Ottawa into a partisan swamp" during his years in power, Liberal Leader Justin Trudeau said Tuesday as he promised a more transparent government if he is elected in October.

"We will make information more accessible by requiring transparency to be a fundamental principle across the federal government," Trudeau said in Montreal on Day 10 of the election campaign.

The Liberal leader accused the outgoing prime minister of leading the "most secretive, divisive and hyper-partisan government in Canada's history."

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"We will clean up his mess."

Trudeau also said a Liberal government would bring substantial change to the scandal-tainted Senate by bringing in a merit-based appointment process.

"Partisanship and patronage need to be eliminated from the Senate," he said. "Harper turned Ottawa into a partisan swamp."

It was no coincidence the Liberals talked about Senate reform. On Wednesday, the trial of embattled former Conservative senator Mike Duffy resumes after a two-month hiatus.

The first witness will be Nigel Wright, Harper's former chief of staff and the man who provided Duffy with $90,000 of his own money to repay his disallowed housing and travel expenses.

Duffy has pleaded not guilty to 31 charges, including fraud, bribery and breach of trust.

Trudeau also promised more free votes as well as greater independence for parliamentary committees.

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"For Parliament to work best, its members must be free to do what they have been elected to do — represent their communities in Parliament and hold the government to account," Trudeau said.