A major argument against the First Republic parties is

The most prominent criticism of the political parties of Nigeria's First Republic (1960-1966) is that they were rooted in regional sentiment rather than national ideology. Each major party drew its support base from a particular ethnic group and geographic region:

• The Northern People's Congress (NPC) was based in the Northern Region and was dominated by the Hausa-Fulani.
• The Action Group (AG) was based in the Western Region and drew its strength primarily from the Yoruba.
• The National Council of Nigerian Citizens (NCNC) was based in the Eastern Region and was predominantly supported by the Igbo.

This ethnic and regional character meant that the parties pursued sectional interests rather than truly national programmes, deepening divisions and contributing to the political instability that ultimately led to the collapse of the First Republic.

While corrupt practices existed, and funding and ideological weakness were also issues, the defining and most frequently cited criticism of First Republic parties is their deep-seated regionalism and ethnic loyalty.