FACTBOX: Scenarios for Serbia after ambivalent vote

(Reuters) - An alliance of pro-Western parties led by the Democratic Party won first place in Serbia's general election on Sunday, slightly ahead of the nationalist Radicals.

Results indicated a scramble to clinch a parliamentary majority and a new governing coalition. Here are some scenarios for what could happen next, with the strength of each possible grouping in the 250-seat parliament:

PRO-WESTERN COALITION/ NATIONALIST- PRO-WESTERN COALITION

SEATS: between 123 and 140

The only way for the Democrats to form a majority government is through an alliance with several ethnic minority parties, and one or two minor partners: the small, ultra-liberal Liberal Democratic Party (LDP) and the Socialists, the once-dominant party of the late Slobodan Milosevic.

The Socialists have indicated they will not formally ally with the LDP -- the only party that says Serbia should accept the secession of Kosovo -- but might be persuaded to support the coalition in parliament in exchange for concessions.

It is unclear if the LDP would agree to such a compromise, which it could justify only as a last resort to keep the Radicals out of power. Such a government would probably be tested by divisions over key issues, such as Kosovo and Serbia's EU future.

THREE-PARTY NATIONALIST COALITION

SEATS: 127

The Radicals floated the idea of an alliance with outgoing Prime Minister Vojislav Kostunica during their election campaign, noting that the premier's opposition to the Western-backed secession of Kosovo made him a natural partner.

If they enlisted the help of the Socialists, the nationalist bloc would have a strong majority in parliament. It would probably put Serbia's bid for European Union membership on ice and have very cool ties with Washington and Brussels. However, they would try to reassure investors that the country is open for business, as foreign investment is key to the economic growth needed to deliver on their populist promises.

TWO-PARTY NATIONALIST COALITION, WITH SOCIALIST SUPPORT

SEATS: 107

Even if the Socialists do not formally join a nationalist coalition, there is a precedent of them supporting Kostunica in parliament, allying themselves with the government in key votes to deliver a majority. Although the partners in such a government would see eye-to-eye in most matters, the Socialists' demands for concessions or key positions for their officials could eventually put pressure on the government.

COALITION OF NATIONALIST WITH PRO-WESTERN PARTIES

SEATS: 132