The measures will also see Skopje become a bilingual city with street signs and official documents in Albanian and Macedonian.
The multiethnic government says the proposed measure is essential for peace and democracy in the country, where ethnic Albanians make up roughly 25 percent of the population. It has also dismissed concerns that the plan -- which has the strong backing of the European Union -- could lead to federalization. The government also labels as unfounded accusations that it is dividing or selling Macedonia.
The speakers at the opposition-organized protest rally attended by 10,000 to 15,000 protesters insisted they do not oppose the 2001 Ohrid peace accords or Macedonia's aim to join the EU and NATO. But they accuse the government of ignoring the will of the people and of trying to rush the measure through parliament.
Nikola Gruevski is the leader of the opposition Internal Macedonian Revolutionary Organization-Democratic Party for Macedonian National Unity (VMRO-DPMNE). He called on protesters to "say no to the territorial division of Macedonia."
"They should not play games with the people," Gruevski said. "We are gathered here tonight to say 'no' to the territorial division the government is trying to impose."
Stojan Andov, leader of the Liberal Party, said that "this kind of thing cannot be resolved by Parliament. This will be resolved by the people."
Prominent personalities and representatives of a number of nongovernmental organizations also took part in the protest, which lasted several hours in the pouring rain.
Some opposition leaders are calling for a referendum on the issue and say they have already collected some 100,000 of the constitutionally required 150,000 signatures needed to initiate the measure.
Yesterday's protest remained peaceful, with police out in force on the streets and organizers calling on protesters to show restraint.
But in Struga, one of the municipalities that would be affected by the new territorial division plan, protesters overnight on 23 July threw petrol bombs and stones. Clashes with police left at least 30 people injured, and the defense minister had to be evacuated under police escort from a meeting in the town.
Ana Petruseva, an analyst with the London-based Institute for War and Peace Reporting, told RFE/RL that -- despite the large protest yesterday -- she does not expect the government to back down. But she adds that it remains to be seen what will happen with the referendum issue.
"If the opposition manages to collect that number, then, according to the constitution, the government would not be able to ignore that and they will have to call a referendum, which will again provoke additional mistrust and ethnic tension, considering the fact that the Albanians have also said that if there is a referendum on the Macedonian side, they will organize something similar among the Albanians," Petruseva said.
Debate on the bill in parliament is expected to continue several days, with the opposition submitting some 150 amendments.
(RFE/RL's South Slavic and Albanian Languages Service/wire reports)