PARIS - The Socialist French presidential candidate Segolene Royal introduces herself as a mother of four who has skillfully juggled family and career. The conservative contender, Nicolas Sarkozy, presents himself as a bold reformer determined to break with the policies of the past.

The French presidential campaign entered its final phase Monday with a series of carefully choreographed TV and radio spots by candidates pitching themselves to undecided voters - nearly half the French electorate. The first round of voting is two weeks away.

Polls indicate Sarkozy is the front-runner for the April 22 vote, followed by Royal. Francois Bayrou, a candidate pledging to bridge France's traditional left-right divide, is third.

The far-right nationalist Jean-Marie Le Pen, in fourth place, appears to be the only of the other 12 hopefuls with a chance of qualifying for the runoff on May 6.

The race between the front-runners is tight, and with so many undecided voters, the outcome is open. A poll published Sunday by the CSA-Cisco agency suggested that 42 per cent of French respondents have not yet made their choice.

Many in France no longer feel allegiance to political parties, historically strong in France, and they are uncertain about who has the right answers for the country's future after 12 years under conservative President Jacques Chirac.

The campaign is being carefully controlled. In newscasts, television and radio stations must give equal time to each candidate. As posters went up at polling stations Monday, workers were obliged to ensure each candidate had an equal number.

In the United States, federal rules generally require broadcast stations to give equal time to candidates who appear on the air. However, the rules do not apply to news programs.

France's audiovisual regulator has allotted each candidate 45 minutes of airtime for publicity spots on public TV and radio channels until April 20 - two days before the first round, when all candidates must stop their campaigning and no polls can be published.

French law does not allow political ads created by third parties; only official candidate ads can be aired.

Royal took a simple approach, addressing voters against a backdrop of blue sky and talking about her background. "I am a woman, a mother of four children, I have my feet on the ground, I am practical, I am a free woman," she said.

Royal's rival Sarkozy steered clear of autobiographical details, focusing in his spot on the main themes of his campaign: employment and immigration.

"Action is my life's passion," said Sarkozy, who pledged to break with policies of the past to resolve chronically high unemployment and better integrate immigrants.

Bayrou, filmed in a close-up shot, said he was uniquely placed to unite the French people. "I want to be the president who brings the French together. It's the only way to rebuild France," he said.

Extreme-right firebrand Le Pen took a more pugnacious tactic, lashing out at the other candidates. He accused front-runners Sarkozy and Royal of latching onto his campaign themes - immigration and national identity - and exhorted voters to choose the "original over the copy."

Of the 12 candidates, seven have less than five per cent support. Candidates who aired spots Monday included Frederic Nihous, a hunter who champions rural traditions; Jose Bove, a farmer-turned-anti-globalization activist; and Philippe de Villiers, a far-right candidate who denounces what he calls "Islamization of France."

Liberation newspaper complained that France's campaign system, by insisting on perfect equality in airtime, was "absurd," saying it would only confuse undecided voters.

"This big fog broadcast on the airways won't do anything to cut down on the record indecision that is the mark of the 2007 elections," the paper said.