Rae, in Newfoundland to speak to provincial Liberals, is keeping up the pressure on the Labrador MP after published reports raised questions about donations made to Penashue's winning campaign.
An Elections Canada review showed Penashue spent $4,000 over his limit of just under $84,500 — and Penashue has admitted to spending more than the legal limit.
Rae has asked the commissioner of Elections Canada to investigate five donations that came from staff at the corporate headquarters of Pennecon Ltd.
Rae says Penashue's overspending gave him an unfair advantage in the campaign.
Penashue won the sprawling riding by just 79 votes.
The Liberal leader had said he wants Canadians to be assured the donations came from the personal funds of the donors and not from the company or from any other source, both of which are prohibited under the Canada Elections Act.
Penashue has said rookie mistakes could be to blame for his campaign's accounting problems, and he says he's working with Elections Canada to sort things out.
His former campaign manager has apologized to Elections Canada for mistakes and missing paperwork.