Another general election defeat, another Conservative leadership contest.

For battle-weary Tory activists, Michael Howard's decision to quit, triggering the hunt for a new leader, had a horribly familiar ring to it.

John Major in 1997 and William Hague in 2001 precipitated months of turmoil when they resigned immediately after leading the Tories to defeat. The party fears Mr Howard has consigned them to the same fate.

Things are different this time, though. Mr Howard can and did legitimately claim that the Conservatives are on the road to recovery.

In 1997 they lost 178 MPs and in 2001 made a net gain of only one. This time, they have clocked up net gains of more than 30 seats, taking the total number of Tory MPs to approaching 200. Tim Yeo, shadow transport and environment secretary, said: “This was the first general election since 1997 that we have made real net gains.”

Nevertheless, there was anger at Mr Howard's unexpected decision to quit. Tory grandees had urged him to stay on to avoid triggering a fresh round of in-fighting over the direction and future leadership of the party.

Many Tories had hoped to train a spotlight on Labour's vastly reduced majority and raise questions about how long Tony Blair could hang on as prime minister.

Such considerations were all but drowned out by news of Mr Howard's departure.

Sir Malcolm Rifkind, the former foreign secretary who has been returned as MP for Kensington and Chelsea, said he was “saddened” because he believed Mr Howard still had a “personal contribution” to make as leader. “I am also sad because I am concerned that we may get thrust into an early debate about personalities which will divert attention from a much more important immediate issue which is to analyse both the successes and disappointments of yesterday,” he said.

Months of uncertainty are inevitable as the party seeks to change the rules on its leadership elections, before embarking on finding a replacement for Mr Howard.

The Tory leader's announcement took even senior party officials by surprise. Sir Michael Spicer, the chairman of the 1922 committee of backbenchers who will have a crucial role in the rule change and ensuing leadership election, was on Friday checking the small print of the Conservative constitution for details about how the overhaul of the rules would be handled. He said: “It's come as a bit of a shock to most people but I can see why he's done it.”

Modernising Tories have been pushing for a change to the rules for some time, arguing that they give too much say to party members.

The traditional bent of most members has meant they have endorsed right-wingers such as Mr Hague and Mr Duncan Smith.

Updating the rules is a complex business that takes time, but the hope is that Mr Howard's successor will be ensconced in good time to fight the government in the European referendum expected next spring.

By then it will be clear whether the Tories have opted for a candidate who believes just “one last heave” is needed to win power or one who sets out to transform the party.

Those on the centre and left of the party are clear a radical appraisal of what it stands for is urgently required. Sir Malcolm said the Tories needed to debate their identity. “It includes another heave but it's got to be more than that.” Damian Green, the modernising former frontbencher, said: “The results mean that one more heave would be a disastrous strategy. Modernisation needs to involve changing what the party talks about in terms of policy and the tone it uses about issues that matter to people.”

But there is no obvious modernising candidate to embrace that challenge. What's worse, pro-reform MPs believe the voluntary wing of the party will refuse to back a rule change. “Turkeys don't vote for Christmas,” muttered one MP. Raymond Monbiot, chairman of the National Convention, the party's network of voluntary activists, said “there's absolutely no intention of the volunteers being out of any of this”, but insisted that he and his colleagues backed a change.

If they fail to do so, the modernisers fear they could end up saddling the party with a leader who chooses not to broaden the Tories' appeal, only to pay the price at the ballot box next time.