NEW DELHI (AFP) - With a combined age of 157, the two men vying for the post of Indias prime minister are having a high old time lobbing ageist stones at each other from their respective glasshouses. Incumbent Manmohan Singh, 76, of the ruling Congress Party and 81-year-old LK Advani of the hardline Hindu Bharatiya Janata Party (BJP) have both made efforts to appear the more spry and energetic on the campaign trail. The Oxford-educated Manmohan underwent multiple heart bypass surgery in January, but made a speedy recovery and has not missed the chance to bring up the five years he has on his opponent. Manmohan attributed Advanis accusation that he was Indias weakest prime minister to his rivals ripe old age and suggested he change astrologers as he was clearly too old to change his views. Advani, meanwhile, has been photographed lifting weights in front of supporters and has tried to reach out to younger voters with a blog. Although both were born in present-day Pakistan, they took markedly different routes to reach the corridors of power in New Delhi. Unlike Advani, a career politician with activist roots, Manmohan is regarded as an accidental prime minister, a technocrat with an unblemished reputation who rescued India from the brink of bankruptcy but seemed destined to keep a low profile. His anointment in 2004 by Sonia Gandhi, after she refused the post, has led Advani to label Manmohan a puppet of the Nehru-Gandhi dynasty. The challenge of heading a rocky coalition government means Manmohan has been criticised for his low-key leadership style. Its a little unfair, said sociologist Andre Beteille, who worked with Manmohan Singh at the Delhi School of Economics. He has had to accommodate too many pressures from too many sides. Manmohan is widely praised for phasing out Indias rigid socialist economic system in favour of greater liberalisation. Advani, meanwhile, jumped straight into politics as a teenager by joining the Rashtriya Swayamasevak Sangh (RSS), a right-wing Hindu outfit that has groomed many BJP leaders. The self-professed Hindi film buff is considered a hawk by detractors who see his unabashed pro-Hindu policies as incompatible with multi-faith, officially secular India. Opponents ridicule his commitment to building a Hindu temple over the remains of desecrated Babri Masjid in Ayodhya - still a key BJP manifesto pledge despite pressing issues of a slowing economy and dire poverty. Advani led the campaign to rebuild the temple but denied involvement in the demolition, calling it the saddest day of his life. Chandan Mitra, editor of the pro-BJP Pioneer newspaper, said Advanis concept of Hinduism is political rather than religious, and reflects his vision of Indian society. Nonetheless Advani has remained the partys figurehead and is credited with turning the BJP into a viable political force. He served as home minister and deputy prime minister under the BJP-led government between 1998 and 2004.