Former prime minister Stephen Harper has resigned from the board of the Conservative Fund Canada, the financial arm of the national party, just as the party's leadership race begins in earnest.

A spokesperson for the party confirmed Harper has stepped back from the position, one he assumed after his party's 2015 electoral defeat. Maclean's magazine was first to report the development Wednesday.

"The fund thanks former prime minister Harper for his tireless work on the board, and wishes him well. His contributions, support and wise counsel to the board over the past many years has been appreciated," said Cory Hann, a spokesperson for the party.

The board, composed of other senior Conservative operatives such as former Sen. Irving Gerstein (a self-described "proud party bagman") and Ontario Sen. Linda Frum, helps raise funds and sets the budget for the party and its leader.

Frum, who was appointed to the Senate by the former prime minister, told CBC News Wednesday she is still a member of the board.

Harper loyalists in the party declined to comment on his departure Wednesday.

Maclean's magazine columnist Paul Wells reported Wednesday that Harper stepped back from an official party role so he could be more actively involved in the upcoming leadership race.

The magazine, citing an unnamed source, said prospective leadership candidate Jean Charest sought Harper's endorsement in a December phone call but the former prime minister refused to give it.

Harper told Charest, a former leader of the now-defunct Progressive Conservative Party of Canada, that "the party is no longer the party [you] led," the magazine reported. The more moderate PC Party merged with the conservative Canadian Alliance in 2003.

Speaking to CBC's Power & Politics today, Wells said Harper's decision to leave the board was "accelerated" as it became increasingly clear Charest is readying a run for the leadership.

"It's pretty clear that Stephen Harper does not want Jean Charest to be the leader. As a long-time senior Conservative said to me, 'Harper is quitting the fund board so he can block Charest.' That wasn't my language, that was volunteered to me by one of my sources," Wells said.

"Harper cannot himself announce, 'I block thee, Jean Charest.' All he can do is speak his mind, say what he thinks and use his considerable clout within the party to rally opinion. Charest gets to decide if he wants to run against those headwinds."

The Conservative Fund has been a source of controversy in recent weeks.

A source close to the board told CBC News in December that board members were blindsided by a report that party funds had been used to send the children of outgoing Conservative Leader Andrew Scheer to private school.

The fund was in the process of looking into the matter when Scheer abruptly quit his post as permanent leader. The fund's decision to probe the spending and Scheer's resignation were "not viewed as coincidental," the source said.

Dustin Van Vugt left his job as executive director of the party during the fracas over who knew what about the spending. Van Vugt, who brokered the tuition deal with Scheer, has since been replaced by Jamie Girard.

The news of Harper's resignation comes on the day former senior Conservative cabinet minister Peter MacKay announced he'd join the race to replace Scheer as leader. It is not yet known if Harper is prepared to endorse one of the candidates vying for the top job.