By Tarek Amara and Patrick Markey
TUNIS (Reuters) - Tunisia's ruling Islamists rejected on Monday a plan for them to step down pending elections, deepening a confrontation with secular opponents that threatens the most promising democratic transition to have emerged from the Arab Spring.
Tunisia has been in turmoil since an opposition leader was assassinated in July, delivering a blow to hopes for a peaceful outcome to the first pro-democracy uprising in the Arab world.
The Islamist government that replaced Tunisia's longtime ruler Zine al-Abidine Ben Ali had on Thursday cautiously agreed to talks on stepping down, after reading opposition protests as a sign it is time to compromise instead of digging in.
On Monday it appeared to take a step back.
"We cannot accept the threat of pressure from the streets," said Ennahda vice president Adb el Hamid Jelassi. "There should be more guarantees."
Stubbornness was the undoing of its affiliate in Egypt - the Muslim Brotherhood which won office through the ballot box after the overthrow of Hosni Mubarak but alienated the masses and the army by refusing to share power.
In contrast, Ennahda had shared power in a coalition with two secular junior partners and had sought to appease worries that it could impose an strict Islamist agenda impinging on liberal education and women's rights.
But it has alienated many Tunisians who see it has mismanaged the economy and gone easy on hardline Islamists. Its critics say it is playing for time to shore up its position before elections and its decision on Monday bolstered that view.
"We have said that this government would not step down concretely before the completion of the constitution," Rafik Abd Essalem, a senior Ennahda official, told reporters.
The party also said it wanted more guarantees on a date for elections before relinquishing power to an interim government.
Issam Chebbi, a senior official in the opposition Salvation Front, told Reuters on Friday it had accepted "without any conditions" a plan for three weeks of transition talks presented by the UGTT labour union that has been mediating in the dispute.
Frustrated at lack of progress, the 800,000-member union on Sunday threatened to mobilize protests to pressure the government to accept the proposal.
"They don't want to leave, there are plenty of hidden agendas here for Ennahda," said one party leader from the opposition coalition last week as the wrangling continued. "We need guarantees, so there is still plenty of work to do."
After the assassination in July, the second killing of an opposition leader by suspected Islamist militants this year, Ennahda came under mounting pressure and street protests from an opposition emboldened by events in Egypt, where the military overthrew the Islamist president the same month.
A National Assembly writing the country's constitution had almost completed its work before it was suspended a month ago over the political crisis. Deputies got back to work last week though most opposition members stayed away.
Ennahda, still the most well-organized Tunisian political group, has seen its support drop in the small nation where the crisis has eroded an already fragile economic outlook.
But the party, which won 41 percent of the seats in the constituent assembly in October 2011, is still popular and organized enough to hold a 100,000-strong march in August.
While it is split between moderates and conservatives, the opposition is an uneasy tie-up between Nidaa Tounes, a party filled with former regime officials, and leftist parties.
Ennahda, keen to shore up its position, wants early elections. The opposition accuses it of stacking local government official positions with its allies to give it an advantage in any quick election.
Even if the two sides do sit down for talks, a final draft of the constitution, the new electoral law and the date of the election may fuel more disputes.
"There is distrust among all the parties about whether they will be given a fair shot in any elections," said one diplomat. "If there is a technocrat government in place, we need to see how the electoral law is shaped."
Tunisia's economy can ill afford any more drift in its transition with its vital tourism industry still recovering from the revolt. International lenders are demanding reforms to fuel subsidies and bloated public wages to reduce the fiscal deficit.
Another potential worry is the reaction of Islamist hardliners, whose influence has grown as they preach a purist vision of Islam calling for Sharia law. Once persecuted under Ben Ali, conservative Salafists have been allowed to form political parties.
Under pressure, Ennahda has since banned Ansar al-Sharia, a radical group with ties to al Qaeda, blamed for a 2012 attack on the U.S. embassy. But Islamists say frustrations are growing over a crackdown many see as just like the old regime days.
"Tunisia should be a Islamic country under Sharia law," said one young Islamist in a Tunis cafe. "There is some frustration, and not everyone can be patient."
(Editing by Philippa Fletcher)