The incumbent Bharatiya Janata Party (BJP) went into the election as the head of the National Democratic Alliance (NDA), a coalition of over 20 parties. Several other parties in the election not part of the NDA also committed themselves to supporting a BJP led government on matters of confidence.
The main opposition league was led by Sonia Gandhi's Indian National Congress, the long-traditional leftist dominant party in India. The opposition coalition comprised far fewer parties, and its alliances were generally weaker than those of the NDA.
A so-called "third front" of left-wing, socialist and communist parties was also present, although this was not a strong electoral alliance so much as a loose grouping of parties that shared similar ideological viewpoints and had some inter-party cooperation. There were also nearly one thousand candidates of unaffiliated parties, independent candidates and parties who were unwilling to take part in coalitions that stood in the election.

The campaign coalesced around a few key issues. Sonia Gandhi was a relative newcomer to the INC (having been elected to the presidency in 1998) and her leadership had recently been challenged by Maharastrian INC leader Sharad Pawar, on the grounds of her Italian birth. This led to an underlying crisis within the INC that persisted during the election and was capitalised upon by the BJP, which contrasted the "videsi" (foreign) Gandhi versus the "swadesi" (home-grown) Vajpayee.
Another issue running in the BJP's favour was the generally positive view of Vajpayee's handling of the Kargil War, which had ended a few months earlier and had affirmed and strengthened the Indian position in Kashmir. During the past two years India had posted strong economic growth on the back of economic liberalisation and financial reforms, as well as a low rate of inflation and higher rate of industrial expansion. The BJP campaigned strongly on the back of these achievements, as well as cultivating some sympathy for the predicament which had led to the government's downfall.

Perhaps most decisive though in the BJP's campaign was the solid alliance it had cultivated and the relatively strong performance it was able to deliver on regional and local issues. The 1991, 1996, and 1998 elections saw a period of consistent growth for the BJP and its allies, based primarily on political expansions in terms of cultivating stronger and broader alliances with other previously unaffiliated parties; and regional expansion which had seen the NDA become competitive and even the largest vote takers in previously Congress dominated areas such as Orissa, Andhra Pradesh and Assam. These final factors were to prove decisive in the election outcome of 1999.

The voting was conducted over five days. Elections were conducted in 146 seats on the Eastern coast of the country on 5 September, in 123 Central and Southern seats on 11 September, in 76 Northern and Upper-Central seats on 18 September, in 74 North Western seats on 25 September, and in the 121 Western seats on 3 October. Despite some fears of voter fatigue, electoral turnout was comparable with previous elections at 59.99%. Over 5 million election officials conducted the election over 800,000 polling stations, with vote counting commencing on 6 October.

Campaign
Results by alliance
১৯৯৯ৰ লোকসভাৰ আস্থাৰ ভোট
Results