New Delhi, June 17 :    New Delhi, June 17:  Missile man A.P.J. Abdul Kalam launched his presidential campaign here with a string of meetings with a host of leaders, including Prime Minister Atal Bihari Vajpayee. Kalam is expected to file tomorrow his nomination papers for the presidential poll on July 15. His main rival Lakshmi Sahgal, sponsored by the Left, is likely to follow suit on June 21, but a chorus is building up for her withdrawal from the fray. Kalam's meeting with the Prime Minister at his residence was described as a 'courtesy call' by official sources and was followed by a South Indian lunch of idli, dosa, vada, sambar and rasam. The sources added that it was an 'informal' meeting, which steered clear of politics and even science and technology. A couple of days ago, Kalam had conveyed to the Prime Minister's emissary, Vijay Goel, who called on him in Chennai, that he wished to pursue his scientific interests even after becoming President. Home minister L.K. Advani, defence minister George Fernandes, human resources development minister M.M. Joshi and parliamentary affairs minister Pramod Mahajan were present at the lunch, as was the Congress leader in the Rajya Sabha, Manmohan Singh. Sonia Gandhi was invited but she could not make it because of daughter Priyanka's advanced stage of pregnancy. Later in the evening, Kalam called on Sonia and recalled his association with the late Rajiv Gandhi. The Congress president recollected how her husband had set up several technology missions with the help of Kalam. Kalam thanked Sonia for extending her party's support to his candidature. 'It was a one-to-one meeting,' sources said. The scientist also visited President K.R. Narayanan who, according to Rashtrapati Bhavan sources, described him as a 'worthy successor'. Shortly after his arrival at the airport, Kalam told reporters it should be understood that he was now a candidate with the support of all major political parties - the NDA, the Congress, the Samajwadi Party and the BSP. 'So what you see is that people want me,' he said. To complete his political thanksgiving round, the President-in-waiting met Samajwadi Party chief Mulayam Singh Yadav, who had proposed Kalam's name for the post. Kalam did not speak to the media, but Mulayam said it was simply a courtesy call. NDA sources said Kalam was 'advised' not to interact with the media for fear that he might have to face disconcerting questions. There was more than a hint of embarrassment in the BJP at Kalam's media session in Chennai where he asked journalists to repeat lines from the Gita after him and posed questions like why Porbandar was famous. NDA sources said one set of nomination papers, comprising 100 names, will be filed tomorrow and, if need be, another will be submitted later. Along with a dozen senior party leaders, Sonia will file a separate set of nomination papers for Kalam.