Priyanka, 42, has preferred to confine her role to campaigning in Rae Bareli, the constituency of her mother and party chief Sonia Gandhi, and in Amethi, the constituency of her brother, Congress vice president Rahul Gandhi.
But she has not pulled her punches in taking on the BJP's prime ministerial candidate. She had preferred to remain quiet in the initial stages of the election, but as the BJP tirade grew sharper, especially against her husband Robert Vadra for allegedly spurious land deals, Priyanka stepped out of the shadows to take on Modi.
Party workers said that Priyanka has injected an aggressive thrust to the party's seemingly flagging campaign, matching the hard-hitting style of Modi.
Congress leaders and workers say in unison that Priyanka's campaign has enthused party workers too. "The impact has been huge. The party's campaign has picked up. She has been aggressive but in a polished way," a party functionary, who did not want to be identified, told IANS.
He said Priyanka's natural charm and the easy manner of delivering her speech has won over voters. "She speaks less, but is very pointed. Her words have a punch," the functionary added.
He said the party will benefit from Priyanka's campaign in the last few phases of the campaign. "Party workers want that Priyanka should step up her role and campaign all across the country," he added.
Besides taking on the BJP, Priyanka has also been mingling with the people of the two constituencies - sharing a meal with village women in the fields, stepping lightly on a pile of bricks as she goes to chat with villagers - all done with an easy charm as she goes about highlighting the work done by Rahul and appeals for votes.
In reaching out to voters in Amethi, she has sought to blunt the aggressive campaign of the BJP and the Aam Aadmi Party (AAP).
Her speeches and rejoinder to Modi and the Bharatiya Janata Party (BJP) have been played up by the national media, giving a fillip to the Congress campaign. She has also sought to present Rahul in the mould of their father and former prime minister Rajiv Gandhi.
Another Congress functionary said that Priyanka has helped the party cover up on lost ground as the party's publicity thrust in the electioneering has not been "very systematic".
He said the party's publicity effort has appeared less synergetic compared to the BJP's.
"The BJP's publicity effort appears to be in synergy as their advertisements in the print and electronic media and thrust on social media appear part of a thought-out plan. Our campaign does not seem to have created a similar impact," the source said, and added that the BJP was also laying thrust on ground level mobilisation.
He said that Rahul had been stressing a lot on the work done by the United Progressive Alliance (UPA) government in his rallies, but it may not have created the desired impact.
"The constant opposition refrain of policy paralysis during the UPA government appears to have made an impact on voters," he noted.
A union minister IANS spoke to also admitted privately that BJP was "definitely ahead" of the Congress in publicity.
Rahul has led the Congress campaign for the Lok Sabha election and addressed most of its rallies across states. Sonia Gandhi has also addressed rallies, but party sources said she had made fewer public addresses compared to the 2009 Lok Sabha election. Sonia had also cancelled a rally in Maharashtra when she was taken ill.
Congress workers across the country have unanimously said that Priyanka should have launched her campaign earlier, another source said.
"They say Priyanka should have been in the forefront of the campaign from the beginning," he added.
Congress leader Randeep Singh Surjewala said Modi was unnerved due to the resonance of the political campaign and energy generated by Priyanka in Rae Bareli and Amethi.
"Modi is unnerved. He and his strategists are totally frustrated, leading to dirty tricks department (of BJP) rehearsing their old allegations," Surjewala told IANS.
Priyanka herself decides on the place and timing of her campaign, said a source.
Priyanka, who has been campaigning in Rae Bareli and Amethi for over 10 days, had last week come out all guns blazing against the BJP after it released a video targeting her husband over property deals.
Some of Priyanka's anti- BJP and Modi barbs hit headlines.
When they targeted her husband, Robert Vadra, she said the BJP was running like "panic-stricken rats" and that she will not be intimidated by their "lies".
Targeting Modi, she said one needed a heart and not a "56-inch chest" to run the country.
Priyanka had also angrily dismissed Modi's purported "daughter" remarks, saying she was "Rajiv Gandhi's daughter" and did not appreciate the comparison with her father.
Amethi goes to the polls May 7. Polling was held in Rae Bareli April 30.