About 500 jobs at the 161,000 barrels-a-day Petit-Couronne refinery are at risk, the latest industrial headache for the Socialist leader who has vowed to stem rising unemployment by the end of the year.

"It's difficult to find a serious buyer. We must do everything to find one," Hollande told reporters after meeting union leaders in Val-De-Reuil, a town about 110 kilometers (70 miles) north-west of Paris.

"The state will do its duty, but it cannot take the plant over, and the workers know that," he said.

He added the state could at some point provide financing.

Petroplus poses a major test for Hollande's government after it faced criticism over the tactics it used in a two-month battle over the future of ArcelorMittal's (ISPA.AS) Florange steel plant, which unnerved investors in the euro zone's second largest economy and confused France's unions.

His administration is struggling to stop a haemorrhage of industrial jobs which has helped push unemployment to 15-year highs, while curbing public spending and raising taxes to help slash debt in a stagnant economy.

A French court set a deadline of February 5 for interested parties to submit bids for the Petit-Couronne refinery.

Shell RDSA.L, which had a six-month oil processing deal with the troubled plant running to mid-December, has not extended its contract, making the refinery less attractive for buyers due to expensive restart costs.

So far only NetOil, a company led by Middle Eastern businessman Roger Tamraz, has submitted an offer while 7 others have filed letters of intent to buy France's oldest refinery.

Net Oil's offer includes an oil supply deal with BP (BP.L) and an agreement with Hyundai (005380.KS) to upgrade the plant.

Union spokesman Yvon Scornet told reporters after the meeting that Hollande had promised to do everything possible to push the project forward, but had given no guarantees.

TAKING CHARGE

Hollande is trying to win back voters who are increasingly unhappy over the government's handling of the economy and disillusioned by communication gaffes.

A survey by BVA for I>Tele on Friday showed two-thirds of respondents were not convinced by Hollande's New Year's address aimed at reassuring the country over his policies.

Approval ratings for Hollande and Prime Minister Jean-Marc Ayrault hit new lows in December.

Hollande, seen as letting his ministers lead the fight, has been compared unfavourably with his pugnacious, micro-managing predecessor Nicolas Sarkozy.

However, the president, who appointed a new communications advisor on Thursday, appears to have decided to put himself directly in the firing line promising to carry out at least one visit a week across France to show his commitment to battling the economic crisis.

"Today, I have to be more present on the ground," he said. "I have to set the example as I am the first to blame. I am not delegating to anybody else the responsibility of explaining to the French the policies that I am pushing through."

(Reporting by Elizabeth Pineau and John Irish; writing by John Irish; Editing by Ruth Pitchford)

• A Permanent Economic Emergency