"Unka dil sirf kursi mang rahain hai (Modi's heart only seeks power)," Gandhi said at an election rally here in Himachal Pradesh. "For political gains he is using the name of martyrs."
Gandhi, in her maiden visit to the state that will go to the polls May 7, said the BJP's political path would cause disaster.
"You should follow the Congress path, the path of development and prosperity, and strengthen democracy."
Describing the BJP leader as a 'pracharak' or propagandist, she said: "It seems he has started thinking himself to be the prime minister even before the results are out."
Listing out the achievements of the Congress-led UPA government in the past 10 years, Gandhi said her party didn't make false promises.
"It's always working ... for the welfare of the poor."
Modi in his election rallies in the state April 29 appealed to voters to ensure his party's victory in 300 Lok Sabha constituencies.
But his use of Kargil hero Vikram Batra's oft-quoted phrase "yeh dil maange more" sparked a controversy, with Batra's parents and the Congress raising objections.
Modi defended his use of the phrase at a 3D rally held a few hours later saying he would "rather leave politics than insult our martyrs and their parents".
The hill state has four Lok Sabha seats - Shimla, Kangra, Mandi and Hamirpur - and the main contest is between the Congress and the BJP.
In the 2009 election, the Congress won the Mandi seat while the BJP bagged the other three.