Barack Obama arrives in New Delhi on Sunday for an unprecedented second visit to India by a serving US president aimed at consolidating what he has called one of the "defining partnerships of the 21st century".

Obama will be the first US president to be chief guest at India's Republic Day parade, a colourful celebration of the country's military might and cultural diversity, signalling a growing closeness between the world's two largest democracies.

Prime Minister Narendra Modi has invited Obama to co-host a radio phone-in show and is reportedly planning to host a private dinner at his Delhi home for the president, who will be accompanied by First Lady Michelle Obama.

The couple was scheduled to visit the Taj Mahal, India's famed monument to love, but their trip has been cut short to allow Obama to travel on to Saudi Arabia and pay respects to new King Salman.

Modi was a Washington outcast only a year ago, and Obama's three-day visit caps a remarkable turnaround in relations between the two countries after a diplomatic row in late 2013 that saw the Stars and Stripes torched on the streets of Delhi.

In an interview with the India Today magazine ahead of his arrival, Obama said the two countries were "natural partners".

"When I addressed the Indian Parliament on my last visit (in 2010), I outlined my vision for how we could become global partners meeting global challenges," he said.

"I'd like to think that the stars are aligned to finally realise the vision I outlined."

Both sides share a common goal in wanting a counter-balance to China, with Modi seen as taking a more assertive line on India's powerful neighbour than the previous regime.

Obama's trip comes just months after Modi's first official visit to the United States, and with so little time to lay the groundwork it is expected to be stronger on symbolism than on content.

Nonetheless, a deal on intelligence sharing is on the cards and decade-old defence cooperation pact is expected to be upgraded.

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- 'Tangible results' -

Defense Secretary Chuck Hagel said before the president's departure that his trip "may well produce some very tangible and positive results" and promised "more progress" on improving ties.

Climate change and Afghanistan are expected issues on the agenda, while particular focus will be on the economy.

Modi has pledged to make India "the easiest place" to do business and the two leaders will make a joint address to company bosses on Monday.

Modi's election in May 2014 was a potential headache for the US, which had blacklisted the Hindu nationalist for more than a decade after deadly communal riots in Gujarat when he was the state's chief minister.

He was only brought in from the cold last February when the US ambassador travelled to Gujarat once it appeared Modi was likely to end the centre-left Congress party's 10-year rule.

The transformation since has been spectacular, with both men heartened by their meeting of minds on a range of issues in Washington in September.

Modi's November invitation "to have a friend over" for Republic Day was issued via Twitter and Obama's quick-fire acceptance underlined a sense of coordination.

The Indian capital is expected to be under virtual lockdown for the January 26 celebrations.

Obama will watch the parade -- a huge spectacle featuring everything from tanks to camels and tribal dancers -- from behind a bullet-proof glass enclosure with Modi.

A senior police officer who asked not to be named said the measures -- which include airborne radars and rooftop snipers -- were "unprecedented".

Beggars have been cleared from many streets and traders in Connaught Place, the city's central commercial hub, said they had been told to shut down during the US president's visit.

"They won't allow me here on the 26th," said 16-year-old Amit Kumar, who shines shoes on the pavement.

"They don't want any unwanted people on the streets."