West Bengal Chief Minister Mamata Banerjee met Sonia Gandhi and Rahul Gandhi in Delhi on Wednesday.New Delhi: Trinamool Congress chief Mamata Banerjee's visit to Delhi has led to opposition unity on a crucial point - ballot papers instead of EVMs for next year's general elections.

Fifteen opposition parties have decided to raise the issue with the Election Commission, sources said.

The Shiv Sena, fractious ally of the BJP, has also joined the bandwagon, raising questions about which side it would choose next year.On board are the Congress, Akhilesh Yadav's Samajwadi Party, Mayawati's BSP, Sharad Pawar's NCP, Lalu Yadav's RJD, IUML, Arvind Kejriwal's AAP, YSR, south parties DMK, HD Kumaraswamy's JDS, Chandrababu Naidu's TDP, Kerala Congress Mani, Left parties CPI and CPM and Ms Banerjee's Trinamool Congress.The opposition parties will meet on Monday morning in Ghulam Nabi Azad's office in parliament and next week, a delegation will meet the Election Commission, sources said.Sources said the opposition parties came to a consensus after Mamata Banerjee went out for a string of power meetings after landing in Delhi on Tuesday.Those on her list included Delhi Chief Minister Arvind Kejriwal, NCP chief Sharad Pawar, three of BJP's sharpest critics -- Shatrughan Sinha and former union ministers Yashwant Sinha and Ram Jethmalani - and Congress chief Rahul Gandhi and his mother, UPA chief Sonia Gandhi.With her initiative in building consensus on the matter, Mamata Banerjee has again indicated that she is ready for a bigger role on the national stage.The dumping of EVMs is a subject on which many parties have been unanimous since the assembly elections in Uttar Pradesh and a few other states last year.

The Electronic Voting Machines, they contended, had been tampered with to favour the BJP.Their combined protests had pushed the Election Commission to throw an open challenge - asking parties to "tweak" the machines.

There were no takers.Still, Mayawati and Akhilesh Yadav - who suffered huge reverses in the state elections - had maintained that ballot papers and not EVMs be used in the future elections in the country.

Arvind Kejriwal's Aam Aadmi Party, which also made tampering allegations, backed the demand.The battle for ballot papers is the next big initiative of the opposition, which is busy crafting a stable alliance to take on the BJP inside parliament and out.

The draft citizens' list in Assam has already led to a huge confrontation in parliament.