The NDP says its membership has reached a record high of 128,351 in advance of next month's leadership convention, thanks largely to big gains in Ontario and Quebec.

Close to 45,000 Canadians have joined the NDP since October, according to figures released Tuesday. Saturday was the last day people could join the party and still vote in the leadership convention next month.

"We're thrilled with the growth we've seen since the start of this leadership race and it reflects the historic growth we saw in the May 2011 election," said Sally Housser, the interim deputy national director.

"I think it's really exciting for all the people that enjoy the democratic process to have nearly 130,000 who now have the opportunity to vote for the next leader of the Official Opposition."

The NDP had 83,824 members in October, but that total, provided by the NDP Tuesday, does not include more than 2,400 people who were previously identified as "federal" members. The total number of NDP members in September, before the federal members were distributed among the provinces, was 86,545.

When the NDP reported the February figures on Tuesday, the provincial totals included those redistributed members, but there was no breakdown to show how many were redistributed members and how many were new members.

The seven leadership candidates and their supporters have been working hard since the fall to sell memberships.

Ontario added the most members – 14,535 – followed by Quebec, where membership rose to 12,266 from just 1,695, a net gain of about 10,500.

British Columbia still leads the country, with 38,735 members, up from 30,000. Nathan Cullen, the MP for Skeena-Bulkley Valley is the only candidate running for the leadership from that province.

Nova Scotia has 3, 844 members, up from 1,300, Manitoba is up 1,749, Alberta by1,216 and Saskatchewan by 2,335.

Candidates have been recruiting members so they can cast ballots for them at the leadership convention on March 24 in Toronto. Every member of the party gets a vote, which means selling memberships has been a critical part of candidates' campaigns up to now.

"All of the candidates have been working hard in each one of the provinces, so I don't think you can say necessarily that one candidate owns a province or not," Housser said. "Everyone has been working hard all over the place."

All seven candidates had been holding back from releasing statistics on the memberships they've sold, but a member of Brian Topp's campaign spoke out Tuesday.

Ethan Cox said Topp and his supporters are responsible for more than 2,000 of the memberships sold in Quebec since January.

Quebec now 'a very NDP province'

Quebec, the province that elected 59 New Democrats to Parliament last May and helped boost the party to Official Opposition, is a key battleground for membership sales. Despite its massive support for the NDP in the election, Quebec had one of the lowest membership counts among the bigger provinces before the leadership contest began.

There is no provincial wing in Quebec, and this puts Quebec at a disadvantage, according to Thomas Mulcair, the only MP from Quebec still running for leader.

He said in September that the uneven membership distribution was a factor he was weighing in his decision whether to enter the race, which he did the following month. Mulcair, who is well-known in Quebec from his days as a provincial Liberal politician there, has put a lot of his campaign efforts into membership sales there.

Housser said the latest numbers show support for the NDP has been building since the election last spring.

"Quebec is now a very NDP province and we think that's wonderful," Housser said.

The cut-off date marked 35 days until the convention. Members will be able to cast a ballot by mail, on the internet or in person at the convention.

The mail-in ballots won't be counted until March 24, when the regular ballots are counted. Voting packages are now being prepared and will be sent to all members later this month.

In the running to replace the late Jack Layton are: Niki Ashton, Nathan Cullen, Paul Dewar, Peggy Nash, Thomas Mulcair, Martin Singh and Brian Topp.

Pat Martin, a Manitoba MP not publicly endorsing anyone, said the race will certainly heat up now that membership has closed for leadership voting.

"It's getting really exciting," he told CBC's Susan Lunn. "It's anybody's race and it's going to be so interesting now as the alliances and the strategic work begins."

Martin predicts that candidates will increasingly try to differentiate themselves in the final few weeks of the race.

The Liberals and the Conservatives both declined Tuesday to provide their membership numbers.