MISSISSAUGA, Ontario, Oct 16 (Reuters) - Canadian Liberal leader Justin Trudeau, the frontrunner in the race to the Oct. 19 election, said on Friday one of his top priorities if elected will be to repair Canada's relationship with the United States.
Trudeau said relations with Canada's largest trading partner had been damaged by Conservative Prime Minister Stephen Harper's singular focus on promoting TransCanada Corp's Keystone XL pipeline - which President Barack Obama has not backed.
"If I earn Canadians' trust in four days' time, it'll be one of my most crucial priorities to begin once again having a productive and constructive relationship with our closest ally and neighbor," Trudeau said during a campaign stop near Toronto.
The center-left party, once in third place, is now more than 7 points ahead of Harper's Conservatives and 13 points in front of the left-leaning New Democrats, according to some recent polls.
Trudeau, campaigning in the vote-rich suburbs of Toronto, said a Liberal government would focus on increased environmental oversight and reducing climate change emissions in assessing projects like the XL pipeline.
The TransCanada Corp pipeline would carry 830,000 barrels a day of mostly Canadian oil sands crude to Nebraska en route to refineries and ports along the U.S. Gulf. It has been pending for more than six years. Obama vetoed a Republican bill approving the pipeline in February.
Foreign relations have emerged as a key difference in the platform of the frontrunners, with Trudeau saying he would take a more multilateral approach to global issues than Harper, who has distanced Canada from the United Nations.
Harper sent troops to Afghanistan and signed up for the mission against Islamic State with allies including Britain and the United States, but the prime minister said on Friday he was not considering full ground-troop involvement in a combat mission against ISIS in Iraq and Syria.
"We do need people on the ground from the region to take on ISIS but in the short term the reality is this - that area, without military pressure on it, will be a significant risk to Canada for the planning of terrorist attacks not just in the region, not just against our allies, but against our country," Harper said during a campaign stop in Quebec.
Additional reporting by Rod Nickel in Quebec City; Editing by Matthew Lewis