If former Justice minister Jody Wilson-Raybould felt she was being pressured by the Prime Minister's Office to help Quebec-based engineering firm SNC-Lavalin avoid criminal prosecution, she had an obligation to bring those concerns up with the prime minister, Justin Trudeau said Tuesday.
Wilson-Raybould announced her resignation in a tweet.
The list also includes David Lametti, who replaced Wilson-Raybould as federal attorney general in a January cabinet shuffle, the prime minister's chief of staff, Katie Telford, and his principal secretary, Gerald Butts.
SNC-Lavalin faces charges of fraud and corruption in connection with almost $48 million in payments made to Libyan government officials between 2001 and 2011. She was previously attorney general and minister of justice.
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But in a letter to the prime minister announcing her resignation on Tuesday, Ms Wilson-Raybould said that she is "aware that many Canadians wish for me to speak on matters that have been in the media over the last week".
A report last week alleged that PM Justin Trudeau's office pressured her for intervention in a case against engineering group SNC-Lavalin.
Her resignation is a potential blow to Trudeau as he faces re-election this year.
"We welcome the ethics commissioner's investigation", the prime minister said following an event in Vancouver, Wilson-Raybould's hometown. He has denied directing Wilson-Raybold to arrange such a deal.
Scheer called on Trudeau to waive solicitor-client privilege to allow Wilson-Raybould to speak freely on the matter.
Her resignation could trigger another cabinet shuffle and is likely to cast a long shadow over the upcoming election campaign. The committee is scheduled to consider the motion on Wednesday.
Since these allegations came out last week, Justin Trudeau has claimed that he never directed Wilson-Raybould in any way to come to any specific conclusion on the SNC-Lavalin case but that he welcomes the ethics commission investigation so that Canadians can maintain their confidence in the government.
At the time she was federal justice minister and attorney general.
"Justin Trudeau promised Canadians he would change the way politics worked in Ottawa, but instead his Liberal government continues to prioritize helping insiders and the rich get ahead".
In her letter, Wilson-Raybould thanked her staff, officials and Canadians who supported her while in cabinet and concluded: "Regardless of background, geography, or party affiliation, we must stand together for the values that Canada is built on, and which are the foundation for our future".