A pair of polls suggest Charlie Angus and Guy Caron may have significant momentum in the NDP leadership race—at least among certain current members—even though Jagmeet Singh boasts the strongest fundraising and endorsement list.

But Quito Maggi, president of Mainstreet Research, which did the survey, freely admits the poll has flaws. Maggi's company did not have access to current membership lists, instead calling lists of past NDP donors publicly available from election finance commissions and screening out non-members. In most jurisdictions those lists exclude smaller donors, skewing the survey pool.

Perhaps most critically, the pool doesn't include new sign-ups. That flaw may particularly underestimate Singh's campaign, which is premised on growth and may have the financial resources to carry out its strategy. The registration deadline is midnight Thursday.

Although the poll is flawed because only a sub-set of existing NDP members were surveyed, an apples-to-apples comparison can be made to a survey of the same list last month. That comparison shows momentum within the survey group.

Between July and August, both Angus and Caron are up 7 points among these member-donors. Singh has gained 2 points. Ashton is down 4 points. Peter Julian, who withdrew last month, held 12% support in the July survey. The undecideds have barely budged, holding at about 35%.

For what it’s worth, the August survey gives Angus 42% support among the survey group, Niki Ashton 28%, Guy Caron 17% and Singh 14%.

But Angus' campaign shows other signs of momentum. Reportedly, his team is submitting heaps of new member forms to NDP provincial offices. And, in recent days, Angus' messaging has started to endorse ideas from Caron and Ashton. That’s a typical front-runner strategy used to build a bridge for second or third round support.

Voters can cast on-line ballots in weekly rounds until a candidate hits 50% support. After each round the candidate with lowest support is knocked-out. First-round balloting opens September 18 and results are announced October 1.

A bridging strategy from Angus could present a threat to Caron and Ashton. Back-pats feel great, but Angus' request for second round support could get converted into a squeeze play—a demand for first round support.

Putting the squeeze on Ashton or Caron would require a compelling reason why Angus requires a higher first round finish. If Angus finds that reason and starts the squeeze, Ashton and Caron would likely start facing disappearing support and disappointing fundraising.

An obvious counter-strategy would be to accentuate differences with Angus. But once the gravity of a front-runner campaign locks-in its tractor beams, it's hard to hammer down supporters hard enough to prevent many from getting pulled up.

To escape Angus’ orbit, Caron and Ashton may need a bolder effort that disrupts Angus’ political gravity or uses it to sling-shot to the top tier. That strategic problem is oh-so common for New Democrats regularly confronted with the ‘red-door, blue-door’ strategy deployed by Liberals.

Meanwhile, Singh's campaign will be working flat out to hit their growth targets by Thursday’s cut-off. About 65,000 Canadians voted in the NDP’s 2011 leadership election, a 51% turnout of 128,000 eligible voters.

The next major focus is an August 27 French-language debate in Montreal. Campaigns will have received updated lists reflecting new sign-ups. We won’t know really how many sign-ups each campaign has generated, but they’ll have a good idea. Watch for the tells.

Tom Parkin is a former NDP staffer and social democrat media commentator