Newly-appointed PN interim secretary general Francis Zammit Dimech has called on members to give their all for the party.
He was speaking during his first meeting with the Nationalist Party's sectional committees at the Pieta headquarters.
Dr Zammit Dimech said the party was experiencing challenging times that were also full of opportunities.
"The party is calling on every party member and all those of good will to come together and provide the country with worthy tools for the benefit of its people."
Briefing those present, he said the executive committee will meet on Saturday to discuss the necessary changes in the party's structure and organisation that would allow the PN to become an effective opposition to the government.
Five council assemblies will meet in the coming days to discuss reform proposals that would later on be discussed by the general council.
In a separate statement, the Żebbuġ sectional committee welcomed Dr Zammit Dimech's appointment.
Dr Zammit Dimech also met Repubblika and discussed "matters of mutual concern" including the "call for truth and justice in the case of Daphne Caruana Galizia", the civil society NGO said.
Repubblika said it engaged with all parties that expressed interest in dialogue with civil society on good governance and the rule of law.