TUNIS, Tunisia - Tunisian polling firms have declared Beji Caid Essebsi, 88, an official from previous regimes, as the winner of Sunday's presidential runoff, cementing his dominance over a country where his party already controls Parliament.

The runoff election marks the culmination of a four-year-long rocky transition to democracy after Tunisians overthrew dictator Zine El Abidine Ben Ali in 2011, kicking off pro-democracy uprisings around the region in what became known as the Arab Spring.

Only in Tunisia, however, has the transition to democracy remained on track, with elections for a permanent parliament held in October and the first round of presidential elections a month later.

The Sigma Conseil company's exit polls, which have consistently come close to matching official results released later, gave Essebsi 55.5 percent of the vote and his opponent Moncef Marzouki, the outgoing interim president, 44.5 percent. Other polling companies gave between 52 and 54 percent to Essebsi.

Marzouki's campaign said Sunday's election was too close to call, and the official results are expected by Monday night. Marzouki congratulated Tunisia for its election and said the country has "banished the fake elections of the past which were won by percentages of 99.99 percent."

Celebrations began immediately after polls closed at Essebsi's party headquarters with fireworks, cheering crowds, and lines of cars, horns blaring. Essebsi struck a conciliatory note, urging Marzouki's supporters to work with him to rebuild the country.

"The future begins today!" he said, saluting Marzouki and the people who voted for him. "What is important is what we do today and tomorrow for Tunisia and all its children. We must work hand in hand."