OTTAWA/BRAMPTON, Ontario (Reuters) - Having gone from third place in the polls to front-runner just days before Canada’s election, Justin Trudeau’s center-left Liberals are bracing for what would be a hectic and painful transition from the political wilderness to government.

Liberal leader Justin Trudeau greets supporters during a campaign stop in Brampton, Ontario, October 16, 2015. REUTERS/Chris Wattie

Liberal sources, who asked not to be identified, said on Friday and earlier this week that the transition team included close Trudeau aides Gerry Butts, Katie Telford, Cyrus Reporter and Mike McNair - though official talk of any preparation for the prime minister’s office is forbidden.

“We have to stay focused and any hint of arrogance or entitlement will be avoided,” said a senior party member.

Voted out of office almost 10 years ago and holding just 36 of 308 seats in Parliament heading into the election, the Liberals would have little more than two weeks to transition to government if they manage to oust Prime Minister Stephen Harper’s Conservatives on Oct. 19.

“This sets the trajectory of a government. If you get it wrong, it’s difficult to recover,” said David Zussman, a former Liberal official who took part in the transitions after the 1993 and 1997 elections.

Trudeau, the 43-year old telegenic son of former Liberal Prime Minister Pierre Trudeau, took over the party in 2013 when it was in a shamble and quickly turned it into a serious contender.

According to an e-mail from the Liberal campaign’s co-chair seen by Reuters after it was leaked to the Canadian Press, the transition team must find cabinet ministers - while trimming the roster from almost 40 to around 25 - and appoint officials to key political posts.

Zussman, who wrote a book on transitions and who has talked to the Liberals and the opposition New Democrats this year, said Trudeau’s aides should have started preparatory work many months ago and by now would have a thick binder.

“There are a huge number of issues that have to be dealt with quickly and so clearly the more planning you’ve done, the faster you can work through it,” he said in a interview.

Other likely members of the transition team, said the Liberal sources, are former Bank of Canada governor David Dodge, former top finance ministry bureaucrat Scott Clark as well as Matthew Mendelsohn of the Mowat Centre, an independent public policy think-tank.

Dodge said he was not on the team, Clark said he had no idea who the members were while Mendelsohn did not respond to a request for comment.

Michael Robinson, who chaired the transition team when Paul Martin succeeded Jean Chretien as Liberal prime minister in 2003, said the cabinet appointments were a big job.

“It takes 10 days to a couple of weeks to vet those people so if you want to swear in your cabinet in two or three weeks, you need to get going right away,” he said.

Once the cabinet is sworn in, the new government will focus on the so-called Speech from the Throne, a list of priorities that is read out to a new session of Parliament.

“It’s relatively simple in this case because you have an election platform, which is (the basis for) your speech from the throne,” said Robinson.