Long accustomed to bad blood between its Greek and Turkish communities, Cyprus is now mired in a new controversy that may have compromised the best chance for peace in a decade.

For once the argument is not directly between the Turkish minority and the Greek majority on this strategic, east Mediterranean island that has been partitioned since 1974 when the Turkish Army invaded and occupied 37 percent of the land.

Rather, the controversy pits members of the Greek Cypriot community, 82 percent of the island's population, against each other.

An unlikely alliance between the right-wing Democratic Rally and the communist Progressive Party of the Working People, known as AKEL, is locked in constitutional and political battle with Spyros Kyprianou, president of the Republic of Cyprus which since 1974 has functioned without Turkish Cypriot participation.

Rally leader Glafkos Clerides and AKEL's Ezekias Papaiannou, who together control two-thirds of the House of Representatives, have thrown down the gauntlet.

Furious with what they consider Kyprianou's mishandling of summit negotiations at the United Nations in January with Turkish Cypriot leader Rauf Denktash, they passed a parliamentary censure motion, 23 to 12, in February. It demanded that Kyprianou give the House of Representatives control of future negotiations with the Turkish Cypriots or resign and call new presidential elections two years before his mandate expires.

Kyprianou is standing his ground, arguing that constitutionally the government is a presidential one, not a parliamentary democracy.

The Supreme Court is now considering the constitutional aspects of the quarrel, but even if it vindicates the president, Clerides has sworn to continue his opposition and paralyze government business.

"We cannot let this minority government decide the future of the island when the two major parties disapprove of the president's handling," Clerides said in an interview.

Ticking off his longstanding differences with Kyprianou's negotiating approach, Clerides made it clear he believed time was not on the side of the Greek Cypriots, who now face permanent partition of the island.

Independent Cypriot analysts and western diplomats are convinced that Kyprianou miscalculated seriously before and during the summit meeting in New York.

The summit, painstakingly prepared by U.N. Secretary General Javier Perez de Cuellar, centered on a proposed compromise backed by the United States and other western governments.

In return for the Turkish Cypriots' dropping demands for a rotating presidency and half the legislature's seats, Kyprianou was to have signed an agreement in principle for a two-zone federal republic that would have reduced the Turkish area to 29 percent of the island.

Working groups were to tackle such delicate questions as the timetable for the withdrawal of about 20,000 Turkish mainland troops and the rights of refugees, mainly 170,000 Greek Cypriots, to return to their homes, safeguard their property and move freely.

Instead, Kyprianou insisted on reopening questions settled in previous meetings and negotiating issues directly with Denktash. The talks collapsed.

A month before the summit, Kyprianou, whose Democratic Center Party commands less than 20 percent of the Greek Cypriot electorate, broke off the so-called minimum program, or working agreement with the communists. He apparently hoped to pick up strength from the center and split Clerides' party behind a tougher stance on negotiations.

Instead of being the hoped-for golden opportunity to form an anti-Turkish front, the tactics backfired.

As both AKEL and the Democratic Rally predicted, Denktash withdrew his proffered concessions which, in any case, were opposed by the Turkish Cypriot right wing.

Despite opposition from the United States and other permanent members of the U.N. Security Council, Denktash carried out his threat to hold a referendum on a new constitution as well as presidential and parliamentary elections in his breakaway, self-styled Turkish Republic of North Cyprus.

With the new constitution approved by 70 percent of the voters earlier this month, and victory virtually assured in the presidential and parliamentary elections scheduled for June 9 and 23, Denktash is further consolidating his state's claims to equal status, even if only Turkey has recognized it so far.

He has said that the starting point for any future negotiations is accepting his state as an equal with the internationally recognized Republic of Cyprus.

Denktash is in a strong position to sidestep the expected efforts of the United Nations and western governments to get the negotiations started again.

As his foreign minister, Necati Munir Ertekun, said in an interview, "Who are we to negotiate with? A Kyprianou who represents a minority view? The Greek Cypriots must put their house in order before we can have meaningful talks."

Even Andreas Mavromatis, director general of Kyprianou's Foreign Ministry, conceded in an interview that the political crisis "does have an adverse affect on very sensitive negotiations." But he insisted that talks with the United Nations had "overcome some difficulties which had cropped up in January," while declining to provide details, and that negotiations could resume despite what he called the illegal referendum on the other side of the island.

AKEL and the Democratic Rally threaten to block the annual budget debate that starts in October. Galanos said in an interview the government could find funding from month to month "within the constitution" to keep itself going.