The Netherlands and Belgium oppose any moves to integrate Serbia, saying the country has shown insufficient co-operation with the UN war crimes tribunal at The Hague.
The tribunal is still searching for Ratko Mladic and Radovan Karadzic, who led the Serb faction during Bosnia's civil war in the early 1990s.
A proposed Stabilisation and Association Agreement would offer trade and co-operation advantages to Serbia, as well put it on track for open membership talks with the EU.
Supporters of the deal believe that signing the agreement before Serbia holds its second round of presidential elections on February 3 would give a boost to Boris Tadic, the pro-Western incumbent.
Growing support
Support for Tomislav Nikoli, Tadic's nationalist opponent, has grown amid dissatisfaction with international support for Kosovo's independence drive.
"We should ... help Serbia on its approach to the European Union," said Dimitrij Rupel, the Slovenian foreign minister.
"One of the forms of such assistance, or a sign of closeness, should be a signature of [the] Stabilisation and Association Agreement in the coming days."