In what ways have political parties contributed to the constitutional development of Nigeria?

• Political parties formed government in their
  various regions under the 1951 constitution. This
  formed the basis for self government in 1957 and 1959 and
  eventually independence in 1960. 
• Political parties provided the leadership for
  constitutional development i.e. their members spearheaded
  agitation for constitutional reforms e.g. 1946 Richards
  constitution in Nigeria was criticised for Sack of
  consultation. This was subsequently corrected in the 1951
  constitution. 
• Parties initiated popular opposition against
  colonial government e.g. the Richards constitution of
  1946 was described by party leaders as containing
  obnoxious laws and these were removed in the 1951
  constitution. 
• They provided political education through
  rallies and news papers owned by their leaders. 
• The political parties provided leaders who
  attended constitutional conferences for the attainment
  of political independence e.g. the Ibadan conference of
  1951 and the  
  London conference of 1953 and 1957
  Generally, 
  1. parties manifestos helps the government of a
     country in formulating its policies.
  2. It helps in passing information on government
     policies to members of the public.
  3. It helps to appoint leaders and personnel to
     the legislative council.