Which major factor was responsible for the dramatic victory of Indira Gandhi in 1971 elections?

Although the Congress’s position was very weak in the electoral contest of 1971, it had something that its big opponents lacked. it had an issue, an agenda, and a positive slogan: 

Garibi Hatao in contrast to opposition’s Indira Hatao. This proved to be a major factor responsible for the dramatic victory of Indira Gandhi.

Major factors responsible for the dramatic victory of Indira Gandhi were:

(i) The positive slogan of ‘Garibi Hatao’. (remove poverty)

(ii) Indira Gandhi focused on the growth of public sector.

(iii) Abolition of princely privileges.