The War Resisters Support Campaign says federal officials have told Kimberly Rivera she must leave Canada by Sept. 20.
Michelle Robidoux, a spokeswoman for the War Resisters Support Campaign, says border services notified Rivera of the decision on Thursday.
Robidoux says that means the government does not believe Rivera's claims that she will face harsh penalties if she is deported to the U.S.
However, there is still no decision on Rivera's humanitarian compassionate grounds claim.
Rivera, the first female U.S. war resister, fled to Canada in 2007 to avoid further military service.
She had initially arrived while on leave but then applied for refugee status.
The War Resisters Support Campaign says two other Iraq war resisters who were deported, Robin Long and Clifford Cornell, faced year-long jail sentences upon their return.
A spokeswoman for Immigration Minister Jason Kenney said in an email that the federal government does not believe the U.S. subjects its soldiers to persecution.
Rivera lives in Toronto with her husband and four children.
Robidoux says Rivera is meeting with her lawyer today to discuss her options.
Rivera did not comment on the ruling but is to hold a news conference Friday morning.
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