Addressing a rally in the heart of Mumbai, Prime Minister A.B. Vajpayee today targeted NCP chief Sharad Pawar, saying his alliance with Congress showed ‘‘Dal mein kuch kala nahin balki puri dal hi kali hai.’’He said Pawar, who split from the Congress on the issue of Sonia Gandhi’s foreign origin, was indulging in the worst form of opportunistic politics. Pawar owed an explanation to the nation, he added.Vajpayee said his party had been raising the foreign origin issue as it was the view of the BJP that under no circumstances should a person of foreign origin hold the offices of the President, Vice-President or Prime Minister. He said Pawar, who quit the Congress on the very same issue, has now aligned with Sonia. ‘‘I feel there is a hidden agenda. Pawar must explain to the nation, as to why he entered into an agreement with Sonia Gandhi,’’ he said.He said when Sonia failed to dislodge his government, she, along with the Opposition, indulged in levelling baseless allegations against him and the Government. In the process, said Vajpayee, she lost her credibility as the Leader of the Opposition. He further said: ‘‘Congress alliance with DMK is nothing but a desperate bid to claim power. It had earlier blamed the Karunanidhi-led party of being hand-in-glove with the forces that assassinated Rajiv Gandhi and pulled down the I.K. Gujral government.’’ During his 45-minute speech, Vajpayee also spoke of Mumbai’s problems and showered praise on Speaker of the dissolved Lok Sabha Manohar Joshi for ‘‘efforts’’ to help transform Asia’s biggest slum, Dharavi. Politicians like Joshi were making efforts, but Mumbai was losing its lustre, he said. ‘‘We will have to do more work. A new airport is underway, Rail Vikas Corporation is also functioning, development plan of Dharavi is underway, but we will have to put in more efforts,’’ he added.Also present at the rally, Shiv Sena chief Bal Thackeray said electoral and judicial reforms were the need of the hour. He said the electorate should exercise their franchise in favour of a party instead of individuals. The EC should then decide the quota of MPs, the choice of which should be left to the parties. This would end corruption.