New Democrats won’t be the only ones tuning into the party’s leadership convention this weekend. It’s likely the Liberals will be keeping a careful eye on who’s chosen to succeed Jack Layton, the leader who died of cancer just months after helping his party claim Official Opposition status in the House of Commons.

With the Conservatives squeezing the Liberals on the right and the NDP elbowing in on the left, the traditional centre of Canadian politics has less space than in the recent past.

Steve MacKinnon, former national director of the Liberal Party of Canada, says a leader who can consolidate and build on the NDP's success last May will make the Liberals' challenge bigger as they try to rebuild their own party.

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"So much about Canadian — and other — politics is leader-driven these days, and so it's obviously a very pivotal choice and it will have a big impact on not just the Liberal Party but every other party," MacKinnon said. "I'll be looking to see sort of what strain within the NDP predominates — the pragmatic strain or the doctrinaire strain — and what kind of face they choose to project to Canadians."

At the same time, he said, "you can't put too much emphasis on the choice of the NDP leader. I think most of the cards with respect to the future of the Liberal Party are in our hands."

Socialist or social democrat?

New Democrats are likely to consider which leader will be able to hang on to its Quebec seats, after winning 59 on May 2, up from one. At the same time, while the party was founded in the Prairies, it now finds itself with no seats between Winnipeg and Edmonton.

With perceived frontrunner Thomas Mulcair, a former Quebec Liberal politician, the NDP could further squeeze the Liberals. He's also seen as the surest bet to hanging on to the newly won Quebec seats.

Robert Asselin, associate director of the University of Ottawa’s graduate school of public and international affairs, says the leadership candidate with the most potential is Mulcair — with a few caveats.

"He's the best politician and he understands how politics works, so I think in terms of positioning the NDP in the next election, he would be probably the most able person the NDP could choose," the former Liberal staffer under Paul Martin said.

At the same time, given the NDP's social democrat principles, Mulcair may have a hard time shifting the party to the centre. One of the most contentious issues at the New Democrats' 50th anniversary convention last summer was whether to replace the term "socialist" in the preamble to their constitution with "social democratic." They managed to avoid voting on the motion by sending it to their executive committee for further review.

"It would be difficult — given their history, given what they believe in — to give a blank cheque to Mr. Mulcair and his mandate to move the party into the centre," Asselin said.

"The NDP has not moved voluntarily to the centre, so what Mr. Mulcair is asking them is a lot, given their history and what they believe in."