MUMBAI, MAY 25: Three former Congress MPs and a former city mayor today resigned from the primary membership of the party to protest against the expulsion of Sharad Pawar, a close aide of Pawar has claimed.The MPs who quit are Suresh Varpudkar from Parbahni, Dada Shelke from Ahemdnagar and Govind Nikam from Ratnagiri, Vasant Chavan, a staunch Pawar supporter, told reporters here.Former mayor Manmohan Singh and two former MLAs, Jayantibhai Parekh and Subhash Thakre, have also resigned from Congress, he added.