Chirac has been president for 12 years and he made his name around the world by spearheading opposition to the US-led invasion of Iraq. His decision to bow out at the age of 74 is the end of an era as younger rivals on the left and right battle it out to take over.

The veteran conservative said in a televised address on Sunday that he would stand down in May after the expected second round of the election and would then seek to serve the country "in a different fashion."

"I will not ask for your votes for a new mandate," he said. "In a different manner, but with the same enthusiasm and passion to act on your behalf, I shall continue to fight our battles -- the battles I have fought all my life -- for justice, progress, peace and the grandeur of France," he said.

Chirac began his political career in 1962 as an advisor to Prime Minister Georges Pompidou, and had his first cabinet post in 1967. He served two straight mandates as president, was twice prime minister and spent 18 years as mayor of Paris.

In 2002 he won re-election with the support of left-wing voters, anxious to keep out far-right leader Jean-Marie Le Pen who stunned the country by qualifying for the decisive second round.

Le Pen said Chirac was "the worst president in the history of France. I am delighted to be losing my best enemy. The proof that he has led the country to disaster is that not a single candidate ... claims his legacy."

Proud of his work

In 2003, Chirac led opposition to the US-led war on Iraq, earning acclaim in many parts of the world and sparking a bitter diplomatic quarrel with US President George W. Bush.

"President Bush wishes President Chirac all the best as he enters life after politics," White House national security council spokesman Gordon Johndroe said after Chirac's announcement. "The United States and France have been and will remain steadfast partners and allies," he added.

Though Bush's fortunes have slumped because of the war, Chirac's also tumbled in 2005, when France rejected the EU's proposed constitution, riots hit the city suburbs, and he was hospitalized with a "vascular incident."

Chirac said that he was "proud of the work which we have carried out together" -- citing in particular improvements for the elderly and the handicapped, reforms of the pension system and reductions in crime and unemployment.

And he called on the country to defend its values in the world. "France is not a country like others. It has particular responsibilities, the legacy of its history and the universal values it helped create," he said.

Still unclear which candidate he backs

As expected, Chirac gave no sign in his 10-minute address whether he intends to endorse the right-wing candidate for the presidency, Interior Minister Nicolas Sarkozy, a former protege who heads the ruling Union for a Popular Movement (UMP).

Sarkozy, 52, has a narrow lead in polls over socialist Segolene Royal but now faces a new challenge from the centrist candidate Francois Bayrou, head of the Union for French Democracy (UDF), whose ratings have surged in the last month.

A poll published in Le Journal du Dimanche newspaper for the first time showed Bayrou on the same score as Royal -- 23 percent -- in the first round of the vote on April 22. Sarkozy was given 29 percent. The two leading contenders qualify for a run-off on May 6.

Misgivings over legacy

While misgivings remain about Chirac's legacy, he commands widespread affection and even political opponents praise his defense of French interests in the world.

"It is a historic moment because a page of history is about to turn. A new page is about to open and the French themselves are going to write it," said Royal.

Bayrou, who served as education minister under Chirac from 1995 to 1997, said that "on foreign policy he was an honorable voice, and a great voice at the moments when France needed one" -- a clear reference to Chirac's defiance of the United States.

However socialist former Prime Minister Laurent Fabius said the Chirac era had been "wasted."

"His long presidency has lost France a lot of time. This is what strikes me most: in relation to the major problems facing France and Europe, a presidency of wasted time," he said.

Chirac will officially leave his post on May 16, when his mandate expires. He has indicated that he would like to chair an international foundation, promoting causes close to his heart such as the environment and non-European cultures.