The MNC was the biggest nationalist party in the Belgian Congo but had many different factions within it which took different stances on a number of issues and was increasingly polarized between moderate évolués and the more radical mass membership.

As a result of the split, the remaining majority of the party took the name MNC-Lumumba (MNC-L) but the split also divided the MNC between the Lumumba-ists who held the Stanleyville region and its faction, which became the MNC-Kalonji (MNC-K; after Albert Kalonji who became its leader after his release from prison) which attracted support in Élisabethville (modern-day Lubumbashi) and among the Baluba ethnic groups.

[7] Both groups competed in the Congo's first parliamentary elections in June 1960, in which Lumumba's party emerged as the largest nationalist faction in the country.

Christophe Gbenye was elected to lead it, but leadership disputes continued to plague the party in subsequent years, with Joseph Kasongo, Charles Badjoko, Gabriel Lassiry, and Antoine Kiwewa all at times claiming to be Lumumba's rightful successor.

While MNC-L persisted longer than other groupings and continued to hold some functions in early 1962, by 1963 nearly all party activity had ceased.

[11] In September 1985, MNC-L, MNCR, the Congolese Democratic and Socialist Party, and other opposition groups declared a provisional government in exile.

However, MNCR head Paul-Roger Mokede rejected his appointment as president of this opposition government, stating that Zaire could not "afford the luxury" of a parallel regime.

[11] In 1996, the leader of one MNC-L faction, Lambert Mende Omalanga,[a] voiced his support for Kisase Ngandu and Laurent-Désiré Kabila.

MNC-L main faction leader François Lumumba used the opportunity to express his hope that his father's nationalist spirit would help the Congolese to defend their country from enemies, considering the then-ongoing M23 offensive.