Theresa May's new suicide prevention minister previously joked about suicide, it has emerged.
Jackie Doyle-Price said she would rather jump off a notorious suicide spot than join Ukip.
The health minister was appointed as the UK's first suicide prevention minister by Ms May on Tuesday but within hours faced criticism over the remark.
Jeremy Corbyn called the comments "inappropriate" and "unacceptable".
Ms Doyle-Price told a local newspaper in her Thurrock constituency that she would rather jump off the Beachy Head cliff in East Sussex than switch party.
She told the Thurrock Gazette: "I would sooner jump of Beachy Head than join Ukip.
"I am a Conservative. I have never run away from a fight and I am not going to start now. The stakes are too high."
The conversation took place in 2014, shortly after another Tory MP, Douglas Carswell, had quit to join Ukip.
Ms Doyle-Price was announced as the head of Ms May's new mental health initiative to coincide with World Mental Health Day.
One of her tasks will be tackling the stigma around mental illness and suicide, but she is likely to face tough questions over her previous comments on the matter.
Around 20 people each year kill themselves by jumping from Beachy Head. Authorities now patrol the area in a bid to deter people planning to jump.
Asked about Ms Doyle-Price's comments, a spokesperson for Jeremy Corbyn said: "Any comment which increases stigma or disrespect or lack of understanding for mental health issues - in particular in this case mental health issues and suicide - is obviously completely inappropriate.
"These kinds of comments are unacceptable."
A Downing Street source said they were not aware of the comments, but added: "There is a serious job she will be taking forward in this very important new position.
"She will have access to some of the nearly £12bn that we already spend on mental health in this country and will want to ensure that services improve further to make sure that people in vulnerable situations get the support they need."
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