Gadkari also asked partymen to defeat the anti-national forces behind the Naxal movement and Pak-sponsored terrorism, saying they were out to divide the country.
The BJP president also said he wanted to see India emerge as a superpower on all fronts, including economic.
"In our country, many questions have cropped up on internal and external security. On the one hand, the Maoist-Naxal movement is posing a threat to democracy in the country and innocents are being killed.
"On the other, there is Pak-sponsored terrorism and terrorist organisations. Terrorists are being sent to India in an attempt to spread terror in our country. We have to keep our nation together. The nationalist spirit needs to be strengthened and from it we must derive strength to fight the divisive forces," Gadkari said at a function organised at BJP office to mark Mukherjee's birth aniversary.
He said Mukherjee made the supreme sacrifice for the unity and integrity of the nation and gave the spirit of nationalism to the BJP, which was the soul of the party.
Former BJP president Rajnath Singh along with other leaders also paid floral tributes to Mukherjee at the function.