Serbiaâ€™s main political opposition party is in disarray after the resignation of its leader.Tomislav Nikolic stood down after hard-line colleagues in the Serbian Radical Party refused to back his call for closer EU ties.
Critics say signing the agreement would mean abandoning Serbiaâ€™s claim to Kosovo, regarded by many as the countryâ€™s spiritual and cultural heartland.
Nikolic lost out in a knife-edge presidential vote in February to his pro-western rival Boris Tadic.
Observers say since then Nikolic has tried to shed his ultranationalist image with a softer line on national issues along with populist pledges to battle corruption and boost the countryâ€™s living standards.
A ratification vote on the Brussels agreement is due to take place in Serbiaâ€™s parliament this week.