The only party opposing the inquiry is National, which lost two seats in Saturday's election and will return to power only if it can make a deal with the nine MPs from New Zealand First, which supports an inquiry.
Devoy went to Geneva last month to ask the United Nations Committee on the Elimination of Racial Discrimination to support her call for an inquiry into abuse. The committee endorsed her proposal.
She showed the Māori Women's Welfare League a photo sent in by an abuse survivor with the words: "I feel let down by the justice system. When I was a youth and even now as an adult for being put in a situation where staff members at a boys home could rape and assault youth and now the justice system is not willing to apologise for what happened to me."
"Earlier this year we called on survivors of state abuse to send us photographs from when they went into care as well as their stories," she said.
"We had an unprecedented response. This photograph is from the first couple of days, hundreds of heartbreaking photos and tragic stories poured into our office."
She said that soon after we launching an open letter on February calling for an inquiry, she was contacted by a friend who had removed many children from their parents in his career as a police officer.
"Susan. All the kiddies we were told to take were Māori kiddies," he told her.
"Until he'd heard their stories - particularly how many were taken for little or no reason at all - he'd never thought twice about the fact that every kiddie he'd dropped off at the children's home was a Māori child," Devoy said.
"He felt sick with guilt at the realisation that many of those children he picked up went on to face years of suffering.
"While we suspect that institutional racism is a big reason why welfare homes were filled with mostly Māori children, until we have a public inquiry we will never know for sure and importantly we won't have the evidence we need to shape our current welfare system.
"The least our Government can do is apologise and investigate. It is appalling that they refuse to do either."