PARIS - With words of shock and shame over Jean-Marie Le Pen's stunning showing, French political leaders of all stripes tucked away their differences yesterday and threw support behind President Jacques Chirac in an attempt to thwart the extreme right's bid for power.

"It is the honor of our country that is at stake," said Dominique Strauss-Kahn, former finance minister and spokesman for defeated Socialist Prime Minister Lionel Jospin, explaining why he would support the conservative Chirac.

He was joined by a host of other defeated presidential hopefuls and their allies, all still not quite able to believe that Le Pen, a man who once called Nazi gas chambers a "detail of history," had outpolled all but Chirac in Sunday's first round to advance to the presidential runoff.

At a news conference yesterday, Le Pen declared himself "the candidate of the French people against the candidate of the system."

"The French by their sovereign power decided to shake up our current system," he said.

Le Pen's second-place finish was a crushing blow to the political left and to Jospin, prime minister for the last five years, who declared the results a "thunderbolt" and announced his resignation from politics. Jospin had been universally expected to advance to the May 5 runoff against Chirac.

The results brought thousands of anti-Le Pen demonstrators into the streets of France's major cities Sunday night, with police in Paris using tear gas to disperse marchers heading for Chirac's Elysee Palace.

Spontaneous demonstrations continued yesterday, especially among the young, in Marseille, Strasbourg, Paris, Toulouse and other cities. "F like fascist, N like Nazi," some cried in Lyon, playing on the initials of Le Pen's National Front party.

Polls predict Chirac will crush Le Pen in the runoff. Still, that wasn't enough to blunt the shock waves reverberating through France.

"NO," cried the leftist daily Liberation on its front page. "The shock" was the headline of Le Parisien.

In a column titled "The wound," the publisher of the respected Le Monde daily, Jean-Marie Colombani, wrote that "France is wounded. And, for many of the French, humiliated."

Some European politicians were expressing shock, although most said they were confident that Chirac would defeat Le Pen in May. The Swedish tabloid Aftonbladet called the election "an insult to democracy."

Le Pen, virulently anti-immigrant and seen by many as racist and anti-Semitic, has long been a thorn in the side of the French political establishment, garnering a typical score of 15 percent in elections. In this, his fourth presidential race, polls had predicted he would place no higher than third.

In a highly fragmented field of a record 16 candidates, Chirac pulled in 19.88 percent of the vote, Le Pen 16.8 percent and Jospin 16.18 percent, according to official results released yesterday. The abstention rate of 28 percent was also a record.

Chirac and Jospin, two well-worn and familiar faces, used platforms seen as virtually indistinguishable: promises to stem rising crime, cut taxes and reduce unemployment. Few people seemed to have a precise idea of what each man stood for.

Not so for Le Pen, who has long blamed immigration - particularly from North Africa - for urban violence and unemployment and uses "French first" as his slogan.

"The problem of insecurity is of exceptional gravity," Le Pen said.

He added that in France, "there is a taboo concerning the link between insecurity and immigration" - a taboo that he was not afraid to break.

"This push, this constant foreign immigration will - if a barrier is not erected - eventually submerge our country, making it disappear, which, of course, we cannot accept," Le Pen said.

Green Party candidate Noel Mamere asked backers to transfer support to Chirac - a request that would once have been unimaginable.

"We're facing a choice that could be considered impossible," Mamere said. "We have a responsibility to society."

Jean-Pierre Chevenement, a former Socialist, said "France should not be abandoned" to Le Pen's party. Francois Bayrou, a conservative rival of Chirac's, met with the president to talk strategy.

Jospin has not endorsed Chirac. However, many close to him have done so. "Jean-Marie Le Pen represents everything I hate, and so I have no hesitation in saying: I will vote for Jacques Chirac," Strauss-Kahn told France-Inter radio.