The Sudanese opposition, known as the Juba Coalition, was set to convene on Wednesday but has postponed its meeting indefinately.
The meeting was to look into coordinating and increasing the opposition's pressure on Sudan's National Congress Party government.
This delay does not signify failure or capitulation, according to the opposition, nor does it imply internal discord.
The opposition renewed its rejection of Bashir's offer to form a broad-based government and demanded a transitional government to deal with the country's exacerbating crises.
Sources in the coalition said that the meeting was postponed because some parties wished to await the referendum's results.