As I noted here, there have been a number of key developments in the NDP's leadership Campaign since last week's rankings. And two in particular have changed my impression as to the relative likelihood of success for the top two candidates, I'll assemble a new set of rankings for this week - while noting that the membership numbers available after Thursday's deadline will likely give us a far better idea where the campaign is headed.

1. Charlie Angus (2)

Angus takes the lead this week for two reasons.

First, the latest Mainstreet poll shows him breaking away from the pack among at its subset of self-identified NDP members. And however much uncertainty there is in trying to assess whether a pollster is reaching the right people, it's certainly worth noting the relative change showing Angus increasing both his percentage support and his lead within a pool that's been polled before.

And second, his broad set of labour endorsements looks significant in a couple of ways. The perception that Angus is the preferred candidate for well-known labour voices may sway a few more voters into his camp early. But perhaps more importantly, but it also offers Angus some validation as a down-ballot option for Ashton and Caron supporters with labour roots.

2. Jagmeet Singh (1)

To be clear, though, there are limitations to how much we can take from any one poll. And while Mainstreet's results contribute to the swap of positions between Angus and Singh, I'd see it as a severe overreaction to put too much stock in Singh's relative placement compared to the other candidates.

That said, this week's membership totals will give us a much better indication whether Singh has assembled enough new supporters to justify the media attention his campaign has been able to secure, or whether we should be taking a much closer look at the prospect of an Angus-Ashton final ballot.

3. Niki Ashton (3)

Meanwhile, the poll results - combined with a lack of other new developments - do serve to lock in the relative positioning of Ashton and Caron for the moment. And while Ashton's campaign figures to be making a strong membership push of its own, it may soon need to reorient itself toward laying the groundwork to build support between ballots.

4. Guy Caron (4)

Finally, Caron remains a credible contender if he can get over the first hurdle of staying on the ballot. And given the importance of building first-choice support among existing members, I'd expect him to push particularly hard to win over Quebec MPs - including those who formerly supported Peter Julian - to persuade current members to decide based on their impressions as to the NDP's prospects in his home province.