OTTAWA — Many NDP supporters may be focused on putting their feet up for the rest of the summer but their party's leadership race is about to enter a critical phase as candidates eye the last leg of the campaign to replace Tom Mulcair.

From now until the finish line, four candidates — Quebec MP Guy Caron, Manitoba MP Niki Ashton, Ontario MP Charlie Angus and Ontario legislator Jagmeet Singh — will be focused on the final push to sign up new members, especially with a looming Aug. 17 cutoff to bring in fresh blood.

"At the end of the day, that's going to be a big factor in who can win this race," said former NDP national director Karl Belanger. "It is crunch time ... When you bring your own people in, it is much easier to know where they are going to end up and who they are going to end up supporting."

If you are able to demonstrate and be the momentum candidate, that is worth its weight in gold.Nathan Cullen

This week, fundraising figures from Elections Canada from the second quarter will also be released ahead of a debate in Victoria — a telling moment in the race, Belanger said, noting it is critical for campaigns to demonstrate momentum when party members are preparing to make up their minds about the next leader.

"If you are able to show your capacity as an individual to raise a significant amount of money, you are showing the potential you have once you become leader and use the organization and infrastructure that is in place to raise even more money," he said.

Veteran B.C. MP Nathan Cullen, a candidate in the last NDP leadership contest, said he is also watching to see how the campaigns demonstrate their strength from here on out, including fundraising prowess and social media savvy.

"If you are able to demonstrate and be the momentum candidate, that is worth its weight in gold," Cullen said. "This is a critical time."

Ashton touts 'incredible response'

In the first quarter, Angus led the fundraising pack with $110,765 followed by Ashton at $65,521 and Caron at $57,235. Singh was not included in this batch because he had yet to enter the race.

Ashton's campaign says it has raised more than $100,000 in the month of July alone — an indication of what's to come, says the MP.

"I will say that if our campaign is any sign, we have seen some incredible response in terms of ... fundraising," Ashton said. "Our campaign has seen that you are able to raise money and ... build support."

All party members are eligible to vote for a new leader, either online or by postal mail. The winner must not only get the most votes, but also must attain at least 50-plus-one per cent of the ballots. As a result, although voting begins in September the balloting could last several rounds, stretching well into October.