Millions of Indians are preparing to vote in a local assembly election billed as the first real test of Prime Minister Narendra Modi’s popularity.
Mr Modi’s Bharatiya Janata Party (BJP) has fielded former policewoman Kiran Bedi as its pick for chief minister.
But polls suggest she is likely to lose to Arvind Kejriwal, an anti-corruption activist who heads his own party.
Mr Modi won convincingly in last summer’s general election, and has ridden a wave of popularity ever since.
Over 13 million people are eligible to vote at 12,000 polling centres.
Security is tight and more than 55,000 police and paramilitary are deployed for Saturday’s vote.
Official results for the 70-member state assembly are due on Tuesday.
In recent months, the BJP has won a string of state assembly elections.
But correspondents say a tough fight awaits them in Delhi, where several surveys have put Mr Kejriwal’s Aam Aadmi Party (AAP) ahead of the others.
The Congress party, which ran the Indian capital for 15 years until 2013, is predicted to come a distant third.
Delhi has been without a government since Mr Kejriwal, the former chief minister, resigned last February, angered that his anti-corruption bill was blocked.
Since then the state has been governed directly by the federal authorities.
Ms Bedi and Mr Kejriwal worked together during the anti-corruption campaign, led by social activist Anna Hazare, but the two have since developed an intense rivalry.
During weeks of hectic campaigning in Delhi, both candidates have promised good governance, ending corruption, and to make Delhi safe for women.
In the previous Delhi election held in December 2013, the BJP won the most seats but fell short of a majority, leaving the AAP – which came second – to form a coalition with the Congress party.
Mr Kejriwal resigned on 14 February after 49 days in office, however, after opposition politicians blocked a bill that would have created an independent body with the power to investigate politicians and civil servants suspected of corruption.