He conquered the Conservatives, but can David Cameron convince voters?

The fatalistic words of Oliver Letwin capture the sense of trepidation that many senior Tories felt as they stood outside the old party headquarters in Westminster's Smith Square on a windswept night in late October 2003. A majority of Conservative MPs had just voted to depose Iain Duncan Smith after a prolonged period of acrimony, division and despair.

Two years later, the party would witness its fourth change of leader in eight years. In David Cameron, the party had voted to change course and beat a path to electability.

And yet, as the polls tighten, it is far from certain whether he will walk into Downing Street in two months' time.

The journey back from the brink of self-destruction has been harsh and unforgiving. Not since the 18th century has the Tory Party been out of office for so long. Their experience in the aftermath of Labour's landslide in 1997 showed a complete ignorance of the lessons the party had learned in the wilderness years of the late 1940s and the late 1970s.

Only under Michael Howard did Tory MPs begin to stand behind the leadership and even this proved tortuous as a third election defeat loomed in 2005.

The subsequent leadership election was a turning point for the Conservative Party. Instead of descending into bitter personality clashes and obsessive debates about Europe, the party went through something of a catharsis before plumping for the untried but attractive proposition of David Cameron.

Its broken relationship with the electorate was debated in an open and mature manner. Cameron emerged as a rank outsider to take the leadership by defeating the frontrunner David Davis, the Haltemprice and Howden MP.

Some of Cameron's team were not optimistic about his chances before the Blackpool conference. "David very, very nearly pulled out because he didn't want to be humiliated," recalls one confidant. "Someone's got to stop Davis," Cameron insisted at the time. His determination against the odds would stand him in good stead as leader. He would certainly need it.

David Cameron's first year as leader was filled with sunny optimism – his long honeymoon coincided with third term blues for the Government. As Blair's exit drew closer, the Tory leadership was increasingly sanguine about its prospects having staked a claim to champion the environment, the NHS and economic stability. The project to cleanse its reputation as uncaring, narrow-minded and obsessed with only a few issues, such as Europe and immigration, was making headway. For the first time since 1992, the party had begun to build a consistent, albeit modest lead in the polls. People were looking afresh at the Conservatives for the first time in well over a decade.

The buoyant mood would not last. A damaging row over grammar schools policy, unease among the grassroots about the leadership's efforts to introduce more women and ethnic minority parliamentary candidates and Gordon Brown's self-assured performance as Prime Minister in the summer of 2007 imperilled the Tory recovery. It took an eye-grabbing policy on inheritance tax, a bullish speech from Cameron and the misjudgment of his opponents to stave off the threat of a snap election.

No sooner had the Tories built a commanding lead in the polls did the leadership find itself responding to a new set of crises. The fall of Lehman Brothers, a deepening recession and the expenses scandal could have derailed the Cameron project. While the financial crisis exposed flaws in the leadership's nascent approach to economic policy, the expenses furore was seized upon as an opportunity to provide a clear public position in getting its own house in order. This Cameron did, although there was little love lost with some resentful Tory MPs.

It is sometimes suggested that David Cameron has had a smooth ride as Opposition leader while the Government has had to contend with the recession and plots from within to remove the Prime Minister from office.

Yet those around Cameron have taken nothing for granted in recent months, not least because of the electoral mountain of gaining 117 seats just to win a majority of one. "We all feel, from the boss down, that it is a big ask to win this election – the figures are immense," recalled one of his aides late last year. "We expect the polls to narrow, and a lot still can happen. It's not a done deal at all." Little did they expect the polls to narrow quite so soon.

At his party's spring forum in Brighton 10 days ago, Cameron acknowledged that the election would be a close fight. Confidence has returned within Labour's ranks – not least because of Peter Mandelson's increasing influence.

If Cameron and his party are to overcome the nerves that have beset them since the beginning of the year, they will need to find clarity on what will be the central issue of the campaign – the economy.

Much will hinge on the quarterly GDP figures next month which will show whether Britain's precarious recovery is intact or in jeopardy. If it is the latter, their call for austerity measures will be strengthened.

Whatever happens, the Tory campaign will need to articulate

a vision for Britain that goes beyond the slogan "Vote for Change". What looked like a one-way fight a few months ago now promises to be one of the closest election battles in decades. It will also really test a party that has come back from the brink.n To order a copy of Back from the Brink: The Inside Story of the Tory Resurrection by Peter Snowdon (HarperPress, 14.99) from the Yorkshire Post Bookshop, call free on 0800 0153232 or go online at www.yorkshirepost

bookshop.co.uk. Postage and packing is 2.75.