Serbia votes in parliamentary elections on Sunday, widely seen as a test of the country's commitment to joining the EU.
Opinion polls suggest that Prime Minister Aleksandar Vucic's pro-EU Serbian Progressive Party (SNS) may get enough votes to form a new government.
But politicians who oppose Mr Vucic's pro-EU course also appear to be gaining ground. They include nationalist Radical Party leader Vojislav Seselj.
He was found not guilty of war crimes and crimes against humanity over the Balkan wars in the 1990s.
That controversial ruling opens the way for him to return to parliament in Serbia. He has called for an alliance with Russia - historically an ally of Serbia, with shared Orthodox Christian traditions.
But a stronger rival to Mr Vucic is likely to be the Socialist Party of Serbia (SPS), led by current Foreign Minister Ivica Dacic. It has been in coalition with the SNS, but formed a separate election alliance with three other parties.
The SPS is generally more cautious over pro-EU reforms than the prime minister's party. Mr Dacic has said that joining the EU should not harm Serbia's relations with Russia and China.
Mr Vucic brought the election forward by two years, saying he needed a new mandate to implement tough reforms required to make Serbia eligible for EU membership.
Early results are expected soon after polls close in Serbia at 20:00 local time (18:00 GMT) on Sunday.
'Enemies in the EU'
Mr Seselj's Radicals failed to win seats in the last two elections, but the firebrand former deputy premier is expected to lead them back into parliament after a virulently anti-Western campaign.
"We do not want to be in the European Union. All Serbia's traditional enemies are there!" he told a rally last month, also lashing out at Nato for bombing Serbia during the 1998-1999 Kosovo war.
And not all members of Prime Minister Vucic's ruling coalition are pro-EU. Some oppose EU integration and advocate closer ties with Russia.
Thus the future of the reforms will be heavily influenced by coalition partners in the new government.
Source: BBC Monitoring