But Trudeau said Prime Minister Stephen Harper's government hasn't done enough to push the project.
"This (federal) government hasn't done a very good job of reassuring either Canadians or our trading partners that we are serious about managing environmental sustainability," Trudeau told reporters after shaking hands with commuters at a downtown subway station early Friday.
"This is the kind of thing we need strong leadership on, and I'm pleased to see Premier Redford taking such a strong and balanced position on that."
The $7-billion TransCanada (TSX:TRP) line would take oilsands crude from Alberta across the U.S. Midwest to coastal refineries in Texas. Labour and industry representatives say the line is crucial to secure a reliable source of oil.
U.S. President Barack Obama is expected to make a decision soon on the fate of the proposed project.
Redford has made numerous trips to Washington to remind decision makers of Keystone's economic benefits and to highlight Canada's environmental record. She has said Alberta charges heavy emitters $15 a tonne for greenhouse gas emissions over set limits and finances many green-energy projects. Critics, however, say the province isn't close to meeting its long-term greenhouse gas reduction targets.
The proposed line has faced sharp criticism from environmentalists in Canada and the United States. Protesters have gathered by the thousands in Washington to say pipelines in general are not safe for the environment, and Keystone should be the line in the sand if industry is to move away from such carbon-intensive operations as the oilsands.
Federal NDP Leader Thomas Mulcair travelled to Washington in March to criticize Canada's environmental record and the pipeline. He has said he'd rather see an Alberta pipeline go east to Canadian refineries than south to create jobs in the United States alone.
Trudeau said Mulcair has not been helpful.
"I'm very hopeful despite the political games being played by the NDP ... that we will see the Keystone pipeline approved soon," said Trudeau.
Trudeau is on his first western swing since he became Liberal leader last month.
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