Newly released numbers by the Conservative Party show that 259,010 members will be eligible to cast a ballot in the party's leadership race.
This represents growth of 150,000 members since the beginning of the January, according to a Conservative Party of Canada statement.
Roughly 250,000 members had been eligible to vote in the party's last leadership campaign in 2004, following the mergers of the Progressive Conservative and Canadian Alliance parties. That vote was won by Stephen Harper, though just over 97,000 members cast a ballot.
In 2013, when the Liberal Party, then in third place, selected Justin Trudeau as its new leader, about 300,000 Canadians were eligible to vote, including the party's new free "supporter" category. Individuals in the new category said they supported the party, but weren't required to pay any money to be members, unlike the other parties.
When the New Democrats last held a leadership race in 2012, about 128,000 members were eligible to cast a ballot.
All 14 candidates will participate in the final official debate of the Conservative leadership campaign in Toronto on Wednesday.
Voting for the next Conservative leader opens on Friday. The winner will be announced on May 27 in Toronto.