Mr Rao is facing possible defeat in the election, with his party in disarray before the growing strength of the right-wing Hindu Bharatiya Janata Party (BJP).
Political observers in New Delhi claim that he is hoping to win back the party's support among the down-trodden lower castes and the minority Muslims who in recent years have deserted the Congress after decades of loyalty. Three of his 15 new ministers are Muslims - including an army hero of India's last war against Pakistan - and several belong to poor Hindu communities.
In some respects, the reshuffle is a signal that nearly all sensible government business, even economic reforms, will be shunted aside for the sake of Mr Rao's re-election campaign.
The Prime Minister has also tried to stave off a possible revolt against him within the party by dissidents who are pushing forward Sonia Gandhi, the Italian-born widow of the late Prime Minister, Rajiv Gandhi. Two of his new choices, S S Ahluwalia and Suresh Pachauri, are reportedly meant to appease Mrs Gandhi, who has lately grown critical of the meandering way in which the Prime Minister has been steering the party.
Mr Rao is also trying to repair the wreckage of his party machinery, which in many regions has been crushed by opposition-party victories in state assembly elections. The Congress, once a juggernaut which overshadowed all other political groups in India, has been chased from its traditional strongholds in the Hindu heartland of northern India, the so-called Cow Belt, as well as in the south.
Several of Mr Rao's new ministers are respected southern strongmen from Kerala and Karnataka, two states that are crucial to his re-election success. Mr Rao also accepted the resignations of four ministers of state who will help to rebuild the party's battered campaign apparatus.
Several influential Congress politicians said privately that Mr Rao's new cabinet choices may be too featherweight to improve the party's lot.
Many Congress supporters claim that the party's only chance of keeping its grasp on power would be for the ailing Mr Rao,73, to step down as party leader and be replaced by someone with more vitality. But as Mr Rao approaches the end of his term - he could call elections any time between February and June - there is no obvious successor, only feuding regional bosses.Reuse content