Boiko Borisov said that the corrupt should now be very afraid
The centre-right opposition party led by Sofia Mayor Boiko Borisov has won Bulgaria's parliamentary election by a wide margin, preliminary results show.
With 99.88% of ballots counted, the Citizens for European Development of Bulgaria (Gerb) have 39.7% of the vote, 22% more than the governing Socialists.
But a BBC correspondent says that while it is a remarkable win, it is not enough for Gerb to govern alone.
Mr Borisov has vowed to end corruption and tackle the economic downturn.
"Those who have stolen should be very afraid... The thieves will go to jail," the 50-year-old former bodyguard told reporters, adding that "updating the budget was the first thing" his government would do.
Last year, Bulgaria lost access to more than 500m euros (£430m) of EU funding for failing to deal with corruption and organised crime.
The BBC's Nick Thorpe says Bulgarians have a habit of voting governments out of office, doing so at each general election for the past 19 years.
Sergei Stanishev has been accused of failing to tackle corruption
In the first election since joining the EU two years ago, the pattern was repeated with Prime Minister Sergey Stanishev's Socialists winning only 17.72% of the votes. In the last election in 2005, they won 33.98%.
Mr Stanishev conceded victory to Gerb and congratulated Mr Borisov after nationwide exit polls were published on Sunday night.
"The results show that the Socialist Party has suffered a serious loss," he said.
The ethnic Turkish Movement for Rights and Freedoms (MRF), a junior coalition partner in the outgoing government, came third with 14.47% and the ultra-nationalist Ataka party fourth, with 9.37%.
Mr Borisov's preferred coalition partner, the Blue Coalition, won 6.73%, followed by the Order, Lawfulness, Justice party with 4.13%.
Gerb also won 26 additional seats in the 240-member parliament in the first direct elections in each of the 31 constituencies. The remaining 209 seats are allocated on a proportional basis.
The electoral commission said on Monday that the provisional results gave Gerb 116 seats in parliament, five short of a majority. Mr Borisov later said he would form a coalition government.