Who is Vajpayee's successor?
There is little doubt that Dy Prime Minister Advani, the long-standing No 2 in BJP's pecking order, is the man at the heart of the mystery.
There have been no prizes for guessing whom Prime Minister Atal Bihari Vjapyee may have had in mind when he said that the Bharatiya Janata Party (BJP) has chosen his successor via an internal consensus although the name is still a secret.
While the Congress has suggested that the person in question may be Gujarat Chief Minister Narendra Modi, it was evidently an observation made in jest to embarrass the BJP.
There is, however, little doubt that Deputy Prime Minister LK Advani, the long-standing No 2 in the BJP's pecking order, is the man at the heart of the mystery.
Hindsight suggests that the first hint that it may be Advani was available when the party unexpectedly decided to include the Ram temple issue in the National Democratic Alliance (NDA) manifesto.
This major departure from the stand taken by the BJP immediately after the fall of the 13-day Atal Bihari Vajpayee Government in 1996 couldn't have taken place but for a big cause.
And nothing can be bigger than a change of guard in India's premier ruling party of the present.
It's obvious that it would have been odd for Advani to take over the reins of the party if the temple, so close to the heart of BJP's and the (Hindu nationalist fraternity) Sangh Parivar's supporters, continued to be on the backburner.
After all, he was the one who set out on his now famous or infamous -- as the point of view may be -- Rath Yatra in 1990 to mobilise support for building the temple.
It was that journey which catapulted the party to power from the fringes of politics. To many traditional supporters of the saffron camp, therefore, Advani should already have been prime minister.
If this wasn't the case, it is because of two reasons. One is the timing of the hawala, or money laundering scandal, which made Advani promise to stay out of contention till his name was cleared.
At a party conclave in Mumbai, he publicly said at the time that Vajpayee would be prime minister. The second reason is that the BJP, and the Jana Sangh before it, has always been a two-man party, with Vajpayee generally credited in the public mind with holding the No 1 position and Advani the second slot.
The Rath Yatra disturbed this order. In fact, Vajpayee lost so much ground at that time that the fiery preacher of the Vishwa Hindu Parishad (VHP), Sadhvi Rithambara, derisively called him "half a Congressman", and an Uttar Pradesh functionary of the party favoured his ouster from the organisation.
But such tremors didn't last long.
The BJP realised soon enough that if it had to stitch together a coalition to gain power in New Delhi, then Vajpayee's wider acceptability within the political class and among the ordinary people would make its task easier.
So, Vajpayee was back again as the numero uno. But he was never really the party's or the Sangh Parivar's favourite.
The manner in which the RSS forced him to reject his choice of Jaswant Singh as finance minister during his first stint as prime minister showed that neither his politics of moderation nor his neo-liberal economic outlook found favour with the Hindu nationalist hardliners.
For several years after that, Vajpayee was under constant attack from the hawks in the Swadeshi Jagran Manch (SJM) and Bharatiya Mazdoor Sangh (BMS).
Advani was always their first choice for the prime minister's post.
It's only recently after Vajpayee's peace initiative with Pakistan struck a chord on both sides of the border that he has become nearly as acceptable within the party and the Sangh Parivar as he is outside.
Otherwise, only a short time ago, he seemed to be very much on a weak wicket when the party compelled him to let Narendra Modi continue as chief minister even after the Gujarat riots and also rejected his preference for then vice president Krishan Kant for the president's post.
It's typical of the man, however, that he has made an announcement about his successor when he is riding high. Even the hardliners in the party and the Sangh Parivar have realised that there is no alternative to him.
There hasn't been a squeak in recent months from the SJM or the BMS. Only the VHP has been making some contrary noises, referring to the present times as a season of appeasement of Muslims, but no one has been paying it much attention.
It's not without significance that Advani's awareness that he is Vajpayee's natural successor has made him try to soften his own hawkish image.
He has been maintaining, therefore, that there have really been no major policy differences with Vajpayee, either during the Agra summit (which the Pakistanis claimed had been sabotaged by Advani) or when the decision was taken to send the Indian cricket team to Pakistan.
Instead, he is on record as saying that the BJP's anti-Muslim image has undermined the party's "ability and capability to rule this country". Not only that, he has said that organisations like the VHP do not understand that "a large area of governance has nothing to do with ideology".
Hence, his view that "a country as vast and pluralistic as India cannot be ruled only by an ideological party such as the Jans Sangh… To rule India, we have to be inclusive".
Since even Vajpayee is often accused of indulging in doublespeak, it is difficult to say how Advani's efforts to present a "kinder, gentler" image will be successful.
But that doesn't mean that his assertions should be rejected straightaway as insincere.
As is obvious, only policies and pronouncements in the future will show whether Advani has become as genuine an admirer of Vajpayee's moderation as he claims to be.