For his opponents, Beji Caid Essebsi's win in Sunday's run-off against incumbent Moncef Marzouki soured what was seen as the culmination of the transition to democracy in the birthplace of the Arab Spring.
The result "reverses the course of history," said Samir Ben Amor, a lawyer and member of the executive committee of Marzouki's Congress for the Republic party.
Essebsi's opponents have accused him of seeking a return to the era of toppled autocrat Zine El Abidine Ben Ali, who clung to power for 23 years, combining authoritarian rule with a degree of prosperity and stability for his people.
Marzouki, a dissident who lived in exile in France for many years, presented himself as the guarantor of freedoms and defender of the revolt that ousted Ben Ali in January 2011.
During campaigning, he repeatedly warned against the danger of electing Essebsi, an anti-Islamist lawyer who held key posts under Habib Bourguiba, the father of Tunisian independence, as well as Ben Ali.
Essebsi's Nidaa Tounes party also includes many members of Ben Ali's old party.
"It's really disappointing," Nejd Ben Hamza, a 34-year-old engineer, said of the presidential vote, lamenting the "short memory" of Tunisians.
"Wasn't Essebsi interior minister under Bourguiba? Didn't he support Ben Ali? Is the crowning moment of the youth revolution, four years later, the election of an 88-year-old?", he said.
"Tunisians have made sacrifices so that finally one of the old guard is going to lead the country," said Ben Hamza, alluding to the roughly 300 people killed during the December 2010-January 2011 revolution.
Essebsi sought to allay such concerns on Monday, saying he was in favour of "completely turning the page on the past".
He has accused Marzouki of representing the Islamists, whom he says have "ruined" the country since the revolution, and many voters appeared to be seeking a return to stability after a sometimes chaotic transition.
Jihadists have claimed the 2013 murders of two secular politicians that had threatened to derail Tunisia's post-Arab Spring transition until a compromise government was formed in January this year.
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FEARS FOR LIBERTIES
The victory of Essebsi, who won 55.68 percent of votes in the second round, has left Marzouki supporters bracing for a reversal of post-revolution freedoms.
"I really fear for our liberties, especially as the same political party will have such overarching powers," said Ali Troudi, a 39-year-old teacher.
Essebsi's Nidaa Tounes won landmark legislative elections in October and is set to form the next government.
"Essebsi talks about counter-terrorism and the prestige of the state," said Troudi. "I'm afraid of a return to repressive practices in their name."
He said he was harassed under Ben Ali for going to the mosque for dawn prayers, making him a target for the old regime which repressed Islamists.
Such fears have triggered clashes between police and Marzouki supporters since the second round vote, particularly in Gabes and Tataouine in the south.
Troudi said that while he did not share Marzouki's ideology, the fact that this "democrat to the core has defended my freedom made him the right person for the next phase, the only one able to bring everyone together whatever their cultural, political or even religious differences."
Supporters of the outgoing president fear that Tunisia's media will be largely deferential to the new leadership, as they were to Ben Ali.
"The media won't be tough on the new president and his party. On the contrary, they will be complicit and that makes me seriously worried about freedoms," said Ben Amor, who thinks the influence of the old guard on the media sector "is one of the reasons for Essebsi's victory."
Throughout his three years as president, Marzouki maintained tense relations with the press.
His camp has accused the media of bias towards his rival and of spreading "rumours and lies" about Marzouki.
But "the fight goes on and we will never give up," vowed Ben Amor.