PARIS — French socialism, forged amid the riots and ideological fervor of 1968, is to be radically recast in the wake of yesterday’s defeat.

The heavyweights of Ségolène Royal’s party did not wait for the result to call for a modernization that could prove as dramatic as Britain’s Prime Minister Blair’s overhaul of the Labour Party in the 1990s.

None have explicitly called for Nouveau Socialisme to echo New Labour, but many appear tacitly to agree with Nicolas Sarkozy that the time has come to break the link with far-left “Spirit of ’68” policies — or face a lengthy spell in the political wilderness.

The man in charge of the socialists, Francois Hollande, who is also Ms. Royal’s partner, has already accepted that his party must change. “We need to come up with something else,” said the man who could be one of the first to go in post-election bloodletting.

Dominique Strauss-Kahn, a former minister who stood unsuccessfully against Ms. Royal for the socialist presidential nomination, went further. “The reformation of the left is absolutely necessary,” he said. “It will mark the construction of modernized socialism and will confirm the entry of the Socialist Party into the 21st century.”

That it has taken seven years for socialists to consider making the leap into the new millennium is likely to lead to bitter recrimination among the movement’s many factions.

In 2002, socialist candidate Lionel Jospin was beaten by farright National Front leader Jean-Marie le Pen in the first round of the presidential election. It was one of the great shocks of modern politics and represented humiliation for the left, as Mr. Le Pen delighted in pointing out, but it was not enough to spur Mitterrand’s successors into action.

Instead, it has taken five more years and the rise of Ms. Royal to challenge the Socialist Party’s heavy hitting dinosaurs — known in France as les elephants — to provoke a consensus that renewal is needed.

The only debate within socialist ranks now is whether to proceed with change through gentle reform or dramatic revolution.

The approach is sure to be determined in large part by their performance in parliamentary elections next month.

In an attempt to challenge Nicolas Sarkozy’s well-organized UMP Party machine, Ms. Royal promised to join forces with the centrists of Francois Bayrou, who came third in the first round of the presidential race.

Not even the hard-line champions of the intellectual left, writing in Le Monde and Liberation, think the socialists can save themselves by forming an alliance with their one-time communist allies. Both papers have instead called for a shift to the center. So far, Ms. Royal has given only glimpses of what that might be in store, with calls for tough tactics to deal with young offenders.

Depending on the results of the parliamentary election next month, her party may decide Ms. Royal is not the right person to emulate Mr. Blair’s reshaping of Labour.

But her campaign has ensured that socialists recognize that a reformer is needed to restore a popularity that after 1968 seemed theirs by right.