Victory for Albania's Socialists empowers them to push economic and judicial reforms vital for membership of the European Union.
Albania's Socialist Party is set to win a majority in parliament following Sunday's election, a partial vote count showed.
Prime Minister Edi Rama's Socialists campaigned to get a mandate that would help them ditch smaller parties and govern alone.
The number of Socialist lawmakers in the 140-seat parliament could rise to 76 compared with 66 in 2013, when little less than half the votes were counted by 1:00pm on Monday.
"According to all data, we shall be in the driving seat," Rama told his candidates for parliament in a message soon after polls closed on what was the hottest day of the year so far in Albania. On Monday morning, he called the vote "an unfinished masterpiece."
Opposition Democratic Party leader Lulzim Basha issued no immediate comment after his party was seen gathering 28 percent of the vote, or 40 seats in parliament.
Voter turnout at 44.9 percent was one the lowest since Albania ditched communism in the early 1990s, probably due to the heat and the end-of-Ramadan celebration observed by Muslims, who account for 60 percent of the population.
Prime Minister Rama and opposition leader Basha had postponed the election by a week after they reached a deal to end a 90-day opposition protest in exchange for letting the opposition into government to prevent election fraud.
Some 400 international observers closely watched Sunday's vote, keen to see Albania bury its image of violent and contested elections. Despite minor incidents, voting appeared generally peaceful and the count progressed slowly but calmly.
The Interior Ministry, however, said hundreds of cases of vote buying and intimidation of voters had been reported. The Socialists and the smaller Socialist Integration Movement (SIM) kingmaker party accused each other of buying votes, intimidating opponents and causing scuffles among their supporters.
International observers were due to hold a press conference later on Monday to give their assessment on whether elections had been free and fair.
Implementing sweeping judicial reforms aimed at rooting out widespread graft will be a priority for the next government as it seeks progress towards joining the European Union.
Rama said last month Albania could get a green light for formal EU talks to start at the end of this year.
"The election campaign was really peaceful and civilised from both sides; they both made only peaceful statements. With peace everybody is a winner," Daut Lumeni, a pensioner, told Reuters Television.