EDMONTON -- New Democrat MPs will return to the House of Commons today after an emotional and divisive weekend that ended up costing Tom Mulcair his job as leader.

Not only does the federal party now have to contend with a potentially divisive leadership race within the next 24 months, it also has to contend with a now very-apparent rift with the governing Alberta NDP.

The two sides did battle over the policy proposals of the "Leap Manifesto," a left-wing pivot that calls for a number of dramatic measures to ease climate change, including an end to pipeline development and fossil-fuel dependency -- ideas not popular in oil-rich but job-starved Alberta.

A leadership battle isn't likely to make matters easier.

Nor will the fact Mulcair plans to remain as leader of the party until a successor is chosen, a decision that could be two years away.

After he failed to garner even a simple majority in Sunday's leadership vote, Mulcair says he plans to continue to work on issues in Parliament for as long as necessary.

There will be other challenges as well, like the financial burdens of an upcoming leadership race as ambitious candidates divide the party's fundraising sources for their own individual campaigns. Some New Democrats also privately worry the party won't be able to raise money with Mulcair as leader.

At the convention, the party signalled it has yet to receive all of its filings from Elections Canada, but it is projecting a debtload of as much as $5 million, a legacy of last year's 78-day election campaign.

The NDP's executive council, its key decision-making team, met on Sunday to initiate a process to determine next steps that will eventually set the wheels in motion for a leadership race.

"The membership's desire for change and renewal has been heard," the party's national director Karl Belanger said in a letter to supporters.

"In the months ahead, we will work tirelessly with you to renew, rebuild, and strengthen this great party of ours. This convention has shown that New Democrats are dynamic, energized, and strongly invested in renewal."

On Wednesday, the caucus is expected to meet as per usual, but they will have a lot more than usual to discuss.

Some members of caucus have already quietly questioned whether it's in the best interests of the party and the goal of moving forward to keep Mulcair at the helm until his successor is chosen.

There's also the question of who will replace him and how soon hopefuls will organize their campaigns.

No one openly challenged Mulcair in the weeks before Sunday's vote, but some of his leadership rivals from 2012, including Manitoba MP Niki Ashton, were pointed in their refusal to endorse his leadership.

Former MP Peggy Nash, another leadership contender four years ago, penned a scathing critique of the NDP's election campaign ahead of the convention.

B.C.'s Nathan Cullen, who finished third in the 2012 leadership race, endorsed Mulcair and said he's no longer interested in leading the party.

Then there's the matter of the Leap Manifesto, which highlighted the ongoing tug of war between those who wish to see the party return to its left-wing socialist roots and others who favour Mulcair's centrist approach as the more likely path to forming a government -- last year's experience notwithstanding.

Peter Julian, a veteran B.C. MP, said Sunday the party is resilient and has already faced adversity including after October's election result and the death of Jack Layton.

"Remember, this is a caucus and a party that lost our leader Jack Layton," he said.

"I came into politics because of Jack Layton. We have gone through what, in many other parties, would be extraordinarily difficult situations. In our party, we have a resilience so we get back to work."