The parliament of Moldova is set to vote in a second and final round of the presidential election, BBC reported.
Last week, the governing Communist Party was one vote short of electing its candidate, Zinaida Greceanii, amid an opposition boycott.
If it fails again this time, the opposition will get its demand - a re-run of last month's parliamentary election that the Communists won.
Violence flared up following the disputed election in April.
Outgoing President Vladimir Voronin has served two terms as president and cannot stand for a third.
The two candidates are from the same governing Communist Party and Mr Voronin has thrown his support behind Mrs Greceanii, the current prime minister.
But the government's desired outcome is far from guaranteed, says the BBC's Gabriel Gatehouse in Kiev.
That is because the opposition parties have refused to field their own candidates, saying they will boycott the vote because they believe April's parliamentary poll was rigged.
In that election, the Communists gained 60 of the 101 votes in parliament - one short of the three-fifths majority needed to elect a president.
Violent clashes later erupted in the streets of the capital, Chisinau, after protesters stormed and set fire to public buildings.
International observers say the election was generally fair.
Mr Voronin's successor will lead the poorest country in Europe - where the average wage is just under $250 (£168) a month - and will inherit an unresolved conflict over the breakaway region of Trans-Dniester.
But Mr Voronin has been elected speaker of parliament - a move analysts say could enable him to retain his hold on power.