With his big lead in fundraising and endorsements, Jagmeet Singh appears to be the front-runner in the federal NDP leadership race. But the only polling data available suggests he is in last place among party members.

Despite this contradiction, Singh could still be the favourite to win.

It all depends on how many new members he can sign up — and the cut-off date is fast approaching. The deadline for registering as a party member and being eligible to vote in the race is Thursday.

A Mainstreet/iPolitics poll published last week — conducted between Aug. 3 and 6, interviewing 1,804 NDP donors who are also party members — found Ontario MP Charlie Angus had the most support.

He led in the poll with 42 per cent among decided respondents, ahead of Manitoba MP Niki Ashton (28 per cent) and Quebec MP Guy Caron (17 per cent). Singh, who currently sits in the Ontario legislature, rounded out the list with just 14 per cent support.

This goes against Singh's perceived front-runner status, awarded due to his fundraising chops — he raised more money in the first six weeks of his campaign than all of his rivals did in the second quarter of 2017 — and large number of endorsements.

As of Friday, Singh had 29 endorsements from current and former federal and provincial legislators, compared to 16 for Angus and nine each for Ashton and Caron. That includes the backing of seven MPs — more than the rest of the field combined.

Pre-existing conditions

But the poll has its limitations. Though the poll includes members from five provincial party lists, the respondents were also drawn from a public list of party donors, which would exclude anyone who has donated less than $200 to the party in any given year. And that represents a significant portion of the NDP's contributor base. In 2016, 65 per cent of the party's contributors gave less than $200.

The poll also excludes anyone who has signed up with the party for the first time during this leadership race. This could also represent a large share of eligible voters. Singh's campaign claims that 75 per cent of his donors have never given to the party before.

Ontario MP and NDP leadership candidate Charlie Angus has led in polls of pre-existing party members. (CBC)

That number, however, also suggests the Mainstreet poll may actually not be far off the mark.

Singh had more individual contributions in the second quarter of 2017 than any of his opponents, bringing in a total of 37 per cent. But if 75 per cent of his tally is excluded, that drops him to just over 400 individual contributors.

That would put him in last place, with just 13 per cent of remaining contributors — lining up with the Mainstreet poll.

Of course, not every contributor to his rivals' campaigns comes from the pre-existing membership base. So his total share of these donors could be somewhat larger. Nevertheless, this suggests that Singh could very well be trailing among pre-existing party members by a wide margin.

The question is: Is that gap too wide?

Turnout could be low

That depends on how many of these pre-existing members turn out to vote.

In the party's 2012 leadership race, only 51 per cent of the 128,351 eligible members cast a ballot in the first round. (And turnout dropped in subsequent rounds, in part due to difficulties the NDP had with its online voting system.)

Getting New Democrats to turn out to vote in a federal leadership race is a challenge due to how the party shares its membership with its provincial counterparts; members in a number of provinces may be more concerned with their local NDP.

In Manitoba, for instance, any recent jump in membership could be due to the ongoing provincial leadership campaign, which will end just two days before voting begins in the federal race.

New members in Ontario could have signed up to participate in the many nomination contests taking place in the province in the run-up to the 2018 provincial election. And B.C. members are just coming off a successful provincial campaign of their own.

It's impossible to know how many of the 50,000 or so members that the national party claimed at the beginning of the race will bother to cast a ballot in the federal contest.

But if we assume turnout is similar to what it was in 2012, it could provide an indication of just how many members Singh needs to sign up in order to win.

Singh needs thousands of new sign-ups

With a turnout of 51 per cent, and using the support levels recorded in the Mainstreet poll, Angus could potentially count on a base of some 10,700 pre-existing members. Singh would have about 3,600.

Ontario MPP and NDP leadership candidate Jagmeet Singh has the most endorsements in the race. (CBC)

That means Singh needs to sign up at least 7,100 more new members than Angus in order to finish ahead of him on the first ballot.

But these need to be members who will vote. Sources with the Conservative Party say that rates of turnout between new and existing members in its leadership vote held earlier this year were roughly even.

If only half of new members vote in the NDP race, Singh would need to register some 14,000 more members than Angus in order to get enough votes out of them to keep him on top.

Though that is a large number, it certainly isn't out of reach. Maxime Bernier, Kevin O'Leary and Kellie Leitch all claimed they had signed up more than 30,000 new members during the Conservative leadership race, working off a base that was about twice as big as the NDP's starting point.

Singh is casting himself as the growth candidate who can bring new members into the party. He also put up impressive numbers in a short amount of time — not unlike O'Leary, though he doesn't have the same national profile.

The biggest indication of whether Singh has been successful will come when the New Democrats reveal the number of members who will be eligible to vote. The party says that number will likely not be announced until next week.

If Singh is to win the leadership, he will need to hope that the number is a big one — and that he is responsible for most of the party's growth. But if it isn't, his difficulty in breaking through with the existing membership could prove to be a major obstacle to overcome.