The Tories' nearly man explains why he is to stand down

When Michael Portillo failed to land the Tory leadership two years ago, he felt a sense of relief as well as disappointment. The one-time protégé of Margaret Thatcher, who seemed destined to follow her one day as party leader, did not really want the job .

"He didn't want to run; we had to break his arm to persuade him to do it," one close ally recalled yesterday after Mr Portillo announced he was standing down as MP for Kensington and Chelsea at the next general election. By doing so, he has left Tory modernisers without a champion and hero. Although he admitted he did not run against Michael Howard this week because he could not win, some Portillistas had not given up hope that he would land the leadership after the next general election.

The pivotal moment in Mr Portillo's rollercoaster career came not in his unexpected defeat in the 2001 Tory leadership contest but four years earlier, when he lost the apparently safe seat of Enfield Southgate to Stephen Twigg, a rising Labour star who was merely cutting his political teeth.

The spectacular result symbolised the change from Tory to Labour Britain. Mr Portillo took his shock defeat well. But it persuaded him to embark on a journey away from his Thatcherite roots, and ended with him emerging as the modernisers' candidate two years ago - the "Pink Portillo", as Norman Tebbit dubbed him after he admitted to a gay relationship during his days at Cambridge University.

The very public journey, ridiculed by his Tory critics, also saw Mr Portillo lose his appetite for "the cut and thrust" of politics. Yet it was not inevitable that his conversion would end his leadership prospects. When William Hague resigned in 2001, Mr Portillo was the front-runner to succeed him and topped the poll in the first round of voting among MPs.

Ironically, allies of Michael Howard studied the Portillo campaign when working out how not to proceed as the fall of Iain Duncan Smith became inevitable in recent weeks. In 2001, the Portillistas claimed they had the support of 100 MPs when they did not, and their arrogance alienated some Tories. In the end, he was squeezed out of the final ballot among Tory members by a single vote by Mr Duncan Smith and Kenneth Clarke.

Since then, he has gained greater pleasure from his work outside the Commons than inside it, notably making television documentaries such as one in which he took on the role of a single mother for a week in Merseyside. His decision at 50 to leave Parliament will give him more time to pursue such projects.

After his political views crystallised at Cambridge, Mr Portillo set off on a traditional path, via the research department at Conservative Central Office. After working as a special adviser to David Howell, Cecil Parkinson and Nigel Lawson, he landed Enfield Southgate in a by-election in 1984 after the sitting MP, Anthony Berry, was killed in the Brighton bomb.

He rose swiftly through the ministerial ranks and joined John Major's Cabinet in 1992 as Chief Treasury Secretary. He served as Employment Secretary before moving to the Ministry of Defence in 1995.

That was the year his reputation as a "plotter" was forged when his acolytes installed telephone lines for a leadership campaign after John Redwood challenged Mr Major for the Tory crown. Mr Portillo apparently told one journalist he would be Prime Minister by Christmas but he lost his nerve, remained in the Cabinet and Mr Major limped on. His own actions contradicted his ill-judged "who dares, wins" speech to the Tory conference, when he was accused of misappropriating the motto of the SAS for political ends. "He didn't dare and so he didn't win the leadership," one critic recalled.

After his 1997 defeat, he returned to the Commons in a 1999 by-election in Kensington and Chelsea, a safe seat for life, made vacant by the death of Alan Clark. The reinvented Mr Portillo was immediately made shadow Chancellor by Mr Hague, articulating a more caring, more socially responsible Conservatism.

It was not a happy period. Mr Hague was persuaded that allies of Mr Portillo were undermining him in the hope that their man would take over. Mr Portillo strenuously denied any plotting, but his relations with Mr Hague were strained.

Even when Mr Portillo left the front bench two years ago he did not lose his reputation as a plotter. Friends of Mr Duncan Smith blamed the recent allegations that he paid his wife too much from public funds on a gaggle of disaffected Portillistas at Central Office.

Mr Portillo blames black propaganda by his enemies. "I am not one who plots and stirs," he said yesterday. "But the fact that I have been accused of it has certainly made me fed up. The role I could play in the Conservative Party has certainly been prejudiced and undermined by people who have put out that sort of story over a long period of time."