The conservative New Democracy party is expected to file a censure motion against Prime Minister Alexis Tsipras's government after it agreed to the tiny Balkan nation being renamed the Republic of North Macedonia.
Greece has long objected to its northern neighbour being called Macedonia because it has its own northern province of the same name, which in ancient times was the cradle of Alexander the Great's empire -- a source of intense pride to modern day Greeks.
Tsipras is to brief parliament on Friday on the agreement he brokered with his Macedonian counterpart Zoran Zaev after months of intensive talks between diplomats.
"This is an agreement that benefits (Greece) and the region," Tsipras said late Thursday in a televised interview on state TV ERT.
"With this agreement, we cancel out any attempt to usurp our history."
Macedonian Prime Minister Zoran Zaev has also hailed the deal, which was announced on Tuesday, calling it a "historic solution".
The agreement still needs to be approved by Macedonia's parliament and pass a referendum there, as well as being ratified by the Greek parliament, a process that will take months.
Macedonia hopes that resolving the bitter dispute will help clear the way for it to join the European Union and NATO.
European Council president Donald Tusk and NATO chief Jens Stoltenberg issued a joint statement on Wednesday voicing the hope that "this unique opportunity to relaunch the wider Western Balkan region's European and Euro-Atlantic integration will not be wasted".
The 20-article document is to be signed by the foreign ministers of Greece and Macedonia, probably in the Prespes Lakes district on the border between the two countries.
The document states that Macedonia's constitution must be revised within the year for the deal to go ahead.
Opponents to the compromise have called for a protest on central Syntagma Square in Athens on Friday and Saturday.
Much of the criticism in Greece has focused on the government's acceptance that the neighbouring country's language and ethnicity will be called "Macedonian".
"The acceptance of the Macedonian language and nationality is an unacceptable national retreat," said New Democracy leader Kyriakos Mitsotakis.
In Macedonia, the nationalist VMRO-DPMNE party has also rejected the deal and President Gjorge Ivanov said he would refuse to sign the text.
Ivanov can veto the Macedonian parliament's decision only once, and has no power to veto a referendum.
Skopje hopes to secure a date to begin accession talks at an EU summit in late June, and an invitation to join NATO in mid-July.
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![33 passengers and one crew member died on the dive boat, Conception [Brian van der Brug/Los Angeles Times/AP]](data:image/svg+xml;charset=utf8,%3Csvg%20xmlns%3D'http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg'%20width%3D'300'%20height%3D'172'%20data-ring-placeholder%3D'1'%3E%3C%2Fsvg%3E "33 passengers and one crew member died on the dive boat, Conception [Brian van der Brug/Los Angeles Times/AP]")
