PARIS - French President Nicolas Sarkozy has promised to force cash-rich companies to pay annual bonuses to millions of workers, an initiative aimed directly at voters unhappy about their falling purchasing power.

His plan to make staff bonuses mandatory at large and mid-sized firms where shareholder dividends have risen was drawn up and rushed out this week in a move that smacks of populism, a year before he faces a crushing battle for re-election.

Critics, including business leaders and unions, say the initiative could be an empty promise, since it sets no rules for determining the size of bonuses. Companies could pay as little as they like, though the government said the payments could amount to 1,000 euros ($1,460) a head.

Analysts say voters may scorn the plan as a poor substitute for pay rises, as households are increasingly feeling the pain of stagnant wages as inflation rises, and many people are angry that Sarkozy has failed to bring down unemployment.

"This is Sarkozy sending a message to working class voters and it's clearly from the standpoint of the election," said Stephane Rozes, head of political consultancy CAP.

Rozes said he doubts whether the bonus plan will alter polls that paint Sarkozy as the most unpopular president in recent times and facing a clear defeat if he runs in 2012.

"Employees want salary rises, not bonuses," Rozes said. "People are suspicious of Sarkozy's words because he's made lots of promises which he hasn't kept. Here, he's asking businesses to do what the state is not doing."

While promising to make it compulsory for firms with more than 50 staff to pay bonuses if they raise dividends, Sarkozy's government is extending a freeze on public sector wage rises until the end of 2012 to help bring down the public deficit.

"When the recovery comes, those who were asked to make an effort should be the first to benefit. It's about fairness," Sarkozy said on Thursday in the northern port of Le Havre.

The size and timing of the private-sector bonuses, and how they would be paid, are to be negotiated company by company and sanctions in the case of non-compliance have not been defined.

CFDT union head Francois Chereque called the plan a "catastrophe" and a way for companies to wriggle out of raising salaries.

"A lot of people will be disappointed," Chereque told LCI television, stressing that the bonus size is undefined.

"Employees will lose out because there will be no pay rise spread over their careers. For businesses, on the other hand, it will be a gift, it will have the effect of a windfall."

Laurence Parisot, head of the Medef employers' group, has called the plan "incomprehensible".

PURCHASING POWER IS 2012 THEME

Shoring up households' purchasing power is emerging as an early theme ahead of official campaigning for the 2012 election, with rivals of all stripes making proposals in recent days.

Sarkozy's longtime arch-enemy Dominique de Villepin, who is expected to run on a centrist platform in 2012, proposed last week creating a minimum welfare benefit of 850 euros a month.

Segolene Royal, who is trying to run for the Socialist Party, said on Wednesday she would seek price caps on an array of basic household products ranging from food to washing powder.

Symbolically, Sarkozy chose the Ardennes -- the northern industrial region where he launched his "work more to earn more" campaign theme in 2006 -- to unveil his bonus plan.

Standing on the floor of a metals foundry, he told a crowd of blue-overalled workers: "When you can give to shareholders, you can give to employees."

Budget Minister Francois Baroin said on Thursday the idea was to put the plan into place before the end of 2011 and a government source said it could affect up to 8 million people.

France already has profit-sharing rules for firms with more than 50 staff. The new plan would be optional for smaller ones.

Finance Minister Christine Lagarde admitted, however, that without an agreement with unions it would probably come down to company managers to set the size of the bonuses.

Sarkozy has been on a drive in recent weeks to lift his poll ratings, taking a tough line on immigration and Muslim issues to try to stem the rise in support for new far-right leader Marine Le Pen, and depicting himself as a fireman for foreign conflicts with military interventions in Libya and Ivory Coast.

Neither strategy has made any difference to polls that show him trailing rivals such as IMF chief Dominique Strauss-Kahn, who may run for the left next year.

A survey by Harris Interactive on Wednesday found Sarkozy would come third in a hypothetical first-round election vote behind Le Pen, with Strauss-Kahn in first place.