With the status of Serbia's relationship with Kosovo and Montenegro soon to come under discussion, Serbian politics may be entering a new and unpredictable phase.

In Serbia, the reformist coalition of Prime Minister Vojislav Kostunica clings to power because it has the informal support of the Socialist Party of indicted war criminal Slobodan Milosevic. But the government will soon face critical tests as it grapples with Serbia's evolving relationship with Kosovo and Montenegro.

With United Nations sponsored negotiations on Kosovo's future status about to begin, Prime Minister Kostunica is in the process of formulating his government's position. Parliament is gearing up to debate the Kosovo question as well.

Still nominally part of Serbia, Kosovo has for six years been administered by the United Nations, ever since NATO forces drove Serbian troops out of the province. Kosovo's 95 percent ethnic Albanian majority demands independence and the major powers have moved closer to accepting that possibility.

But, in Serbia, Kosovo it is an explosive political issue. None of Serbia's many political parties is willing to even discuss the possible loss of the province that is the cradle of Serbia's orthodox Christianity. Privately, however, some Serbian politicians accept that Kosovo will likely split from Serbia. The western powers most involved in the upcoming negotiations insist that the Kosovar Albanians guarantee minority rights and provide access to Serbian religious shrines.

Montenegro is also a problem for Mr. Kostunica. This small and sparsely populated territory is currently loosely linked to Serbia, but it prints its own money and enjoys widespread autonomy. The government wants full independence for the mountainous coastal republic and Montenegro is expected to hold a referendum on independence early next year.

Political analyst James Lyon, the Belgrade representative of the International Crisis Group, says Montenegro will likely separate from Serbia. He agrees with most analysts who predict that Kosovo will also achieve some kind of independence.

Political and economic analyst Miroslav Prokopijevic predicts the loss of both territories may well strengthen the nationalist element in Serbia's politics. He says when elections are held in Serbia, probably sometime in 2006, the extreme nationalist Radical Party will come to power.

"That's for sure. Because according to all polls they enjoy now 35 percent popularity," he said. "And since with our system of proportional representation, with a turnout of 45 percent or lower [in the election], they [the Radicals] will be able to form a government alone. This means they would have at least 126 seats out of 250."

The Radicals, whose leader Vojislav Sesej is awaiting trial for war crimes in The Hague, has long been an ally of discredited former President Milosevic.

Mr. Kostunica, a constitutional lawyer, has presided over a fractious multi-party coalition. Like most reformist politicians, he wants Serbia to be part of the European Union some day.

Preliminary negotiations have begun but Europe and the United States have conditioned further progress on integration into western institutions on the extradition by the end of this year of Ratko Mladic, the former Bosnian Serb military commander who has been indicted for war crimes. Mr. Mladic is believed to be hiding in Serbia.