Bucharest Mayor Traian Basescu claimed victory on Monday in Romania's presidential runoff, pledging to fight corruption and prepare Romania to join the EU by 2007.
Basescu also vowed to fight poverty and restore press freedoms in a victory speech at his party's headquarters after his opponent, Prime Minister Adrian Nastase, conceded defeat.
"The top priority is to fight corruption," Basescu said, adding he would free state institutions from political interference and "put them to work on behalf of the citizens."
"It is the decision of the Romanian people and I respect it," Nastase said, adding that he congratulated Basescu personally on the phone on Monday. "Basescu is the future president of Romania."
Basescu, a 53-year-old former ship's captain, said that he would consolidate ties with the US and Britain to guarantee Romania's security, and that he would also seek good ties with Ukraine, Russia and other former Soviet states.
He said his Justice and Truth Alliance would try to form a parliamentary majority by gaining the support of a party representing ethnic Hungarians and the small Humanist Party, which was previously allied to Nastase, but issued a statement on Monday expressing its independence.
Basescu's victory dealt a major blow to the successors of Romania's communists, who have governed for most of the period since the 1989 revolution.
With all the ballots counted, Basescu had 51.23 percent of the vote, compared with Nastase's 48.77.
President Ion Iliescu, who had supported Nastase, called Basescu on Monday to congratulate him, said Corina Cretu, the president's spokeswoman. Iliescu said the runoff elections were fair and that they confirmed Romania has a working democracy, she added.
The results from Sunday's election sent thousands of Basescu supporters onto the streets in cities around Romania.
In Bucharest, Basescu took part in a rally on Monday night near the parliament, where around 7,000 of his supporters gathered to celebrate.
He promised to free state institutions from political control.
"Police, prosecutors, judges will do their jobs" without politicians telling them what to do, he said.
Basescu added he would appoint his Alliance partner Calin Popescu Tariceanu as prime minister.
The opposition is seen by many Romanians as less connected to the communists who ruled until a violent 1989 revolution, and less tainted by corruption and political foul play.
However, Nastase's Social Democratic Party has overseen a period of economic growth -- and the opposition, during four years in power until 2000, proved unable to reform a system riddled with corruption.
In the parliamentary elections, Basescu's alliance won 161 of 469 seats. Nastase's party won 189, but could be left with just 160 if the Humanists -- who control 29 seats -- bolt from their electoral alliance with Nastase and become independent.
Neither side has enough seats to form a majority, and will need the support of smaller parties. The new parliament met on Monday in its first session.
In an interview with the Ro-manian service of the BBC, Basescu said he would not form a government with the nationalist Greater Romania Party.
Diplomats say US and European officials have explicitly warned candidates not to ally themselves with nationalist party leader Corneliu Vadim Tudor.
Tudor's party is best known for baiting Jews, Hungarians, Gypsies and other ethnic minorities. Recently, Tudor issued an apology for having made anti-Semitic remarks.