Jill McGivering BBC correspondent in Delhi

One of India's leading scientists has filed nomination papers on Tuesday to become India's next president.

Dr Kalam pioneered India's missile programme

The candidature of Dr APJ Abdul Kalam has been the subject of political bargaining for some time, and he now seems certain to be voted into office.

The presidential elections will be held on 15 July.

Dr Kalam, known in India as "Missile Man", has been one of the key architects of India's ballistic missile programme.

For more than 40 years, he has worked on developing a series of short, medium and long range missiles.

He would be India's first president without any political track record at all, but his supporters brush away concerns.

Approved candidate

As the post of president is largely ceremonial, it is argued that political experience does not matter.

Certainly after weeks of speculation, he has now emerged as the front runner, endorsed by both the ruling coalition and the main opposition Congress Party.

He will bring refreshing colour to India's rather formal political establishment.

Dr Kalam has long, unruly grey hair, wears casual clothes and speaks passionately about integrity and values.

He has strong personal discipline, he is a strict vegetarian, teetotaller and a bachelor with a reputation for working day and night. He is also a Muslim.

Religion irrelevant

He has told reporters he does not see his religion as relevant to the presidency.

"I regard myself as an Indian," he says.

But the choice of a Muslim is an important signal at a time the country is still recovering from the worst Hindu-Muslim riots for years.

Analysts have also focussed on his life's mission, bolstering India's defence systems.

A hero of national security seems a relevant choice while so many here are still concerned about the threat of conflict with Pakistan.