Ruth Kelly helped force a compromise over the Embryology Bill
Transport Secretary Ruth Kelly, who is reported to have asked to leave the Cabinet at the coming reshuffle, has repeatedly been at the centre of controversy during her career in government.
The 40-year-old Bolton West MP took up her Cabinet post last July when Gordon Brown became prime minister.
But there had been speculation she could leave the government over her objections to the Human Fertilisation and Embryology Bill - with her very strong Catholic beliefs cited as the reason.
In March of this year, her name was mentioned among Catholic ministers and MPs who would refuse to back the bill.
The prime minister was forced into a compromise, saying Labour MPs could have a free vote on three areas.
Reports that Ms Kelly would vote against the Bill persisted. However, claims that this was the reason for her wish to leave the Cabinet have been denied.
Climbing the ladder
Ms Kelly, who was born in Limavady, Northern Ireland, attended Sutton High School and the private Westminster School.
She went on to study politics, philosophy and economics at Queen's College, Oxford, followed by an MSc in economics at the London School of Economics.
She married Derek Gadd, a local government officer, in 1996.
Her first job was as an economics reporter for the Guardian, where she is said to have spotted that Tory Chancellor Norman Lamont had broken his "golden rule" in the 1992 Budget.
She moved on to the Bank of England, where she was deputy editor of the quarterly inflation report.
She holds a record by giving birth to four children while being an MP.
Her first child was born just 11 days after she took the marginal seat of Bolton West from the Conservatives in 1997.
Once an MP, she joined the Treasury select committee and a year later was made a parliamentary aide to Nick Brown, the then minister for agriculture, fisheries and food.
She became a minister for the first time after the 2001 election - joining Gordon Brown's team as economic secretary to the Treasury.
Ms Kelly was later promoted to financial secretary but took a bigger leap up the government ladder in September 2004, becoming minister of state for the Cabinet Office.
She combined that role with being Labour's deputy election and policy co-ordinator, and was involved in drafting up Labour's manifesto for its third term in government.
Aged just 36 when appointed as education secretary in December 2004, Ms Kelly was the youngest Cabinet minister by 10 years.
Her appointment was questioned following revelations of links to the Catholic conservative movement Opus Dei, which critics accuse of being secretive and elitist - claims members deny.
Ms Kelly rejected calls to quit her job or break off links with the group and said: "It is a private spiritual life and I don't think it is relevant to my job."
As education secretary, she rejected government adviser Sir Mike Tomlinson's proposals to replace GCSEs and A-levels with a new diploma, to the anger of many educationalists.
Ms Kelly ran into enormous political flak - not least from Labour backbenchers - over proposed changes to schooling in England and the introduction of trust schools.
She moved to the post of Communities Secretary in May 2006. Critics said her religious beliefs would guide her judgment in her task of promoting gay rights. But Ms Kelly promised to fight discrimination in all forms.
The following year she was heavily criticised after deciding to send her son to a £15,000-a-year specialist private school to help with his learning difficulties.
The issue of private education has long been controversial among Labour MPs.
And in this particular case it gave ammunition to critics who said the government had reduced the number of special needs schools and pursued a policy of including as many children with special needs as possible in mainstream schools.
Ms Kelly said her decision was a difficult one to take, a decision she knew some would disagree with, but also one that she felt she had to take as she did "the right thing for my son".
She also stressed that her three other children remained in the state sector - and that she expected her son to go to a state secondary school in due course.
When Gordon Brown became prime minister in July 2007, Ruth Kelly moved from being Communities Secretary to Transport Secretary.
It was she who announced that the government had given the go-ahead for the £16bn Crossrail project across London.
She refused to be drawn on whether a road congestion charge would be introduced in Manchester, however - even if residents voted for it in a referendum.
As a Conservative MP, Boris Johnson once said: "I admire the way she has managed to be a real person as well as succeeding in politics. She must be identical twins."