He called for creating a "free and amiable atmosphere" in the party in which it could "take on the challenges easily".
"There should be no room for groupism in the party... we should work together shunning our differences," Vajpayee told the concluding session of the BJP's National Council meeting in Lucknow.
In an obvious reference to the recent 'PM-in-waiting' controversy, Vajpayee said, "Our opponents are challenging us. There is only one way to succeed that we should work in unison."
Exhorting party workers to focus on the forthcoming assembly elections in five states, he said these would "open doors to new possibilites".
Even though he thanked the Uttar Pradesh government for its hospitality to the visiting BJP leaders, Vajpayee attacked the Samajwadi Party-led government for the recent killings of BJP workers.
"We are grateful to the state government for the hospitality but we cannot forget the brutal killings of our party workers only because they belonged to a different party," Vajpayee said.
"Beheading someone in this civilised age cannot even be thought of," he said referring to the murder of a party worker.
Terming the prevailing situation in Uttar Pradesh as a "challenge", he said that the party must prepare itself to face it and restore the earlier position of the party in the state.
Underlining the importance of the politically crucial state of Uttar Pradesh, Vajpayee said that the "road to Delhi goes via Lucknow".
In his 30-minute address Vajpayee heaped praises on the newly re-elected party chief Rajnath Singh and said that he (Singh) had been associated with the organisation as well as with the government.
"Rajnathji is now carrying the responsibilty of taking the taking the party ahead," he said.
Vajpayee's remarks thanking Singh for "granting" him an "opportunity" to address the conclave evoked laughter from the delegates as also from the senior leaders.
When Vajpayee said that he had never held the post of party president, senior leader Murli Manohar Joshi interrupted him saying that he had donned the mantle once.
"Yes only once and that was also the last," Vajpayee replied.
