Spc Hinzman has described the war in Iraq as illegal
Canada is to deport a United States soldier who fled to the country to avoid deployment in Iraq.
Spc Jeremy Hinzman, 29, was told his family's application for refugee status had been turned down by Canada.
His supporters say Spc Hinzman, who had already served a tour of duty in Afghanistan, was the first Iraq war resister to seek sanctuary in Canada.
Some 200 deserters from the US military are believed to have fled to Canada, some living incognito.
Others have sought refugee status.
Lee Zaslofsky, a spokesman for the War Resisters' Support Campaign, a pressure group helping US deserters in Canada, told AFP news agency Spc Hinzman would face "cruel" and "harsh" punishment in the United States.
Deserters from the US military face a court martial and up to five years in prison.
Canada last month deported the first US deserter to have arrived in the country since the war in Iraq. Robin Long is now in detention in the US, awaiting court martial.
Although the parliament in Ottawa passed a non-binding motion in June allowing US deserters to remain, the government has ignored the vote.
The conservative government is said to be keen to avoid angering Washington over the issue.
Tens of thousands of Americans, most of them avoiding the military draft, found refuge in Canada during the Vietnam war.
Canadians in favour of deporting the latest generation of deserters argue that the US no longer has compulsory conscription.