The Bharatiya Janata Party, which has declared that it has launched itself into election mode, is yet undecided about its candidate for the prime minister's post in the event of a snap poll.

"Both Atal Bihari Vajpayee and L K Advani are our top leaders. But the BJP's parliamentary board will decide this (the party's prime ministerial candidate)," senior BJP leader Vijay Kumar Malhotra told reporters.

Malhotra was asked who his party would project as its candidate for the top job following his colleague Yashwant Sinha's remarks to a news channel that a leader of opposition in India does not necessarily become prime minister when his or her party comes to power.

Sinha, who had been virtually sidelined in the party when Advani was its president, cited Congress chief Sonia Gandhi [Images] as an example, saying she too did not become prime minister although she was leader of opposition during the National Democratic Alliance rule.

Asked whether it meant that Advani should not be considered PM-in-waiting, he said, "No, this is not what I am saying. Whenever a decision is taken on the issue within the party and the NDA, you will be told."

"BJP is neither a one-book party or a one-leader party. We have a collective leadership and all decisions are taken collectively," Sinha said.

"You should understand the style of functioning of our party. Atalji is our tallest leader. Advaniji is also our leader. Rajnath Singh is our party president. That is why Atalji and Advaniji will jointly decide on the issue," BJP spokesman Prakash Javadekar told the same channel.

"As soon as elections are announced, Atalji will make the announcement (of the party's nominee)," he said.