Mrs Gandhi was speaking after being reelected the chairperson of the Congress Parliamentary Party.
Congress Parliamentary Party president Sonia Gandhi on Saturday described the Lok Sabha election results as a "political and moral defeat" of Prime Minister Narendra Modi, who, she said, has lost the moral right to leadership.
Addressing newly elected MPs in the Central Hall of Parliament, she said far from taking responsibility for the failure, the Prime Minister intends to get himself sworn in again on Sunday.
She was unanimously reelected as the chairperson of the Congress Parliamentary Party (CPP) with a voice vote during its meeting.
In her speech later, Sonia Gandhi said the Prime Minister had sought the mandate solely in his name to the exclusion of both his party and its allies, but has suffered a political and moral defeat.
"In reality, he has lost the mandate he sought and thereby has lost the right to leadership as well. Yet, far from taking responsibility for the failure, he intends to get himself sworn in again tomorrow. We do not expect him to change the substance and style of his governance, nor take cognisance of the will of the people," she said.
"That is why, as members of the CPP, we have a special obligation to be watchful, vigilant and proactive in holding him and his new NDA government accountable. No longer can and should the Parliament be bulldozed like it has been for a decade now," she said.
Sonia Gandhi said no longer will the writ of the ruling establishment be permitted to disrupt Parliament, whimsically mistreat members or push through legislation without due and proper consideration and debate.
"No longer can and should parliamentary committees be ignored or bypassed like they have been since 2014. No longer will Parliament be muzzled and stifled as it has been over the past 10 years," the CPP chief said.
Observing that the times ahead were challenging, she told the Congress MPs that they have to be alert to prevent any attempts to increase polarisation and erosion of secular and democratic values enshrined in our Constitution by the ruling dispensation. All such attempts have to be thwarted, she said.
Noting that she is deeply conscious of the responsibility all have placed on her once again, Sonia Gandhi said, "This is a very emotional moment for me." She said she has received immense love and affection from the party leaders and assured them saying "I will do my best and more to fulfil the trust and confidence you have continued to place in me".
The Congress leader described this as a renewed opportunity for the party that established parliamentary democracy in the country to bring parliamentary politics back on track.
"In this election, the people have voted decisively to reject the politics of divisiveness and authoritarianism. They have voted to strengthen parliamentary politics and safeguard our Constitution.
"They have voted for the agenda of economic and social justice. That indeed should continue to be our objective and guide," she noted.
The CPP chairperson also said the Congress is being bolstered by the strength of the INDIA bloc allies.
"Our numbers in Parliament have increased significantly. Not only is the Indian National Congress a large contingent in Lok Sabha, but also we are bolstered by the strength of our INDIA partners, some of whom have themselves come back impressively," she said.
She also said the Bharat Jodo yatras were "historic movements".
"Rahul (Gandhi) deserves special thanks for his tenacity and determination to fight on in the face of unprecedented personal and political attacks. He also shaped our narrative on guarantees and protection of the Constitution very sharply," she said.
Mrs Gandhi, however, cautioned the MPs and asked them to reflect on what needs to be done to improve the party's position in the states where its performance has been below expectation.
She also congratulated the newly elected MPs, saying they fought a tough election under the most challenging circumstances. They surmounted many obstacles and campaigned effectively, she noted.
"Your success has given us a much greater presence in Lok Sabha and a more effective voice in its proceedings, both of which will help give greater strength to our participation," she said.
She also lauded the party's campaign where everyone functioned truly as a collective (body). To those who contested but lost this election, she extended full support saying they fought valiantly and did the party proud.
Sonia Gandhi thanked the Congress workers who stood by the party in the most difficult times.
"We salute their courage and commitment. We owe them a debt of gratitude," she noted.
She said the Congress has once again demonstrated its resilience. It was up against a "mighty and malevolent machine" that was doing its utmost to destroy the party, she said.
"It tried to cripple us financially. It carried out a campaign against us and our leaders that was full of lies and defamation," she said.
Sonia Gandhi lauded Congress president Mallikarjun Kharge's role.
"Many wrote our obituaries. But under the determined leadership of Khargeji, we persevered. He is an inspiration to all of us. His commitment to the party organisation is truly extraordinary and we all have to learn from his example," she said.
Mr Kharge later said, "It is a big thing that she (Sonia Gandhi) has been elected as Congress Parliamentary Party chairperson. She will continue to guide us. She continues to serve the party and I salute her for this."
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)