* New premier to lead until elections due in 2014
* Secular, Islamist divisions still raw
* Economic pressure seen as favouring negotiation
By Patrick Markey and Tarek Amara
TUNIS, Dec 19 (Reuters) - A year ago, Mehdi Jomaa was running a successful international business from Paris, making high-tech aerospace components designed to take the danger and discomfort out of flying.
Now that the Tunisian engineer has been named his country's caretaker prime minister, he may need the skills of a career in safety seals and shock absorption to keep the nation that launched the Arab Spring from shaking itself apart before he can steer it through elections intended to cement democracy.
Jomaa's nomination on Saturday came only after months of bitter haggling and still lacks the support of key secularist opponents to the Islamists of Ennahda, the biggest party in parliament which has led interim administrations for two years.
Called home to be industry minister in March when Ennahda brought technocrats into a new government in a bid to ease tensions after Islamist militants were accused of the killing of a secular leader, Jomaa is now trying to form a cabinet that can keep the peace and run a legislative election to be held next year once a much-delayed new constitution has been agreed.
"Poisoned Gift," headlined La Presse newspaper, catching the mood of division that persists after Jomaa was nominated by a panel intended to promote consensus after the assassination of a second secularist in July raised fears of wider violence.
At stake is the stability of the small North African state, whose overthrow of its strongman ruler three years ago inspired uprisings in Egypt, Libya, Yemen and Syria and which now risks being drawn deeper into a messy regional struggle with armed Islamist radicals who have benefited from the upheavals.
Naming a premier gave some relief from months of argument but has deepened secularists' mistrust of Ennahda, a moderate movement modeled on Egypt's Muslim Brotherhood, and could further delay a deal on permanent political institutions.
Providing a push, however, Western powers and international lenders, holding out the prospect of much-needed economic help, have been urging Tunisian leaders to overcome their rivalries.
Major secular party Nidaa Tounes and its allies abstained from the final vote on Jomaa and have threatened to boycott his cabinet. Zied Lakdhar, leader of a leftist party, said the pressure was now on the 51-year-old engineer to heal the rift:
"Did we get the consensus government? No. So it is up to him now to show that he is capable of that," Lakdhar said.
"He has a lot to do, and little time to do it."
Jomaa himself, previously a senior manager at Hutchinson Aerospace, part of France's Total group, has said little in public as he goes about the business of building a new cabinet before he can be formally confirmed in office.
He faces a number of potential disputes, from the make-up of his cabinet to the completion of the constitution, the appointment of election supervisors to a review of appointments in local governments that Ennahda's critics say were partisan.
Particularly tricky may be finding a compromise on the date for an election - Ennahda wants a quick vote - and on the role of the current assembly once it has agreed the constitution. Ennahda wants it to continue to sit until a new body is elected. Some opponents want the old parliament wound up.
Technically, with good will, the process could be completed within weeks. But Tunisian precedent since 2011 argues against that, as seen most recently in the tussle over a new premier.
On the other hand, political leaders agree that restoring stability is urgent. Tourism, a key component of the economy, has suffered along with other businesses since the collapse of Zine el-Abidine Ben Ali's police state. The budget deficit is growing, creditors are impatient and militants pose a threat.
"If this process takes too long then we will end up back at square one," said Lotfi Zitoun, an Ennahda official who noted that the party's Ali Larayedh remains premier until Jomaa can form a cabinet. "A country cannot move forward with two prime ministers, and we need to go forward as soon as possible."
Tunisians' ability to keep negotiating, without the bloodshed seen after other Arab revolts, has seen them held up as a model. In a country of just 10 million, facing Europe and generally more secular than some of its neighbours, compromise on the role of Islam in politics has seemed possible.
Ennahda has shown a flexibility the Muslim Brotherhood found hard to achieve before it was overthrown in Egypt. But having lurched from crisis to crisis, divisions between the Islamists and others over Tunisia's future are still raw.
Islamists reproach opponents like Nidaa Tounes leader Beji Caid Essebsi for having held positions under Ben Ali.
Essebsi in turn condemned the appointment of Jomaa, whose role in the outgoing Ennahda government raises secularists' suspicions. "The results of the dialogue worsen divisions in Tunisia," Essebsi said. "They don't reflect any consensus."
Critics say Ennahda has coddled hardline Salafists accused of killing secular leaders, of attacking the U.S. embassy last year and of seeking alliances with al Qaeda factions which have been active in neighbouring Libya, Algeria and beyond.
The party's most bitter opponents say it is clinging to power with the aim of imposing a theocratic Islamic republic that will erode Tunisia's liberal women's rights and education.
And yet for all the complaints of a lack of consensus, there has been progress. And analysts say there is little incentive for the opposition to walk away from negotiations to complete the final steps to new political institutions.
The constitution is nearly finished. Mainstream leaders on both sides see the ballot box, not the street, as their arena.
And financial pressure may help keep the parties talking.
U.S. ambassador Jake Walles this week urged leaders to form a new government quickly and to finish the constitution. Progress, he said, may ease decisions on U.S. loan guarantees.
International lenders are also watching events closely and are in a position to reward signs of greater stability. The African Development Bank this year cancelled a $300-million credit because of the uncertainty. And Tunisia is still waiting for a second tranche of a $1.7-billion credit from the IMF.
Eurasia Group analyst Riccardo Fabiani said the timetable to elections may yet be delayed. But with a worsening economic situation and pressure from mediators, opposition parties have limited room to reject Jomaa or boycott the national dialogue.
"The risk of failure of the transition as a process remains low," he said. "Jomaa will appoint a technocrat cabinet that will reassure the opposition of its neutrality."