In a major boost to the Congress, four of its senior leaders, including P. Chidambaram and Kapil Sibal, were elected to the Rajya Sabha on Saturday, party sources said.While Chidambaram won from Maharashtra, Sibal got elected from Uttar Pradesh. Colleagues Jairam Ramesh and Oscar Fernandes won from Karnataka.Former additional solicitor general Vijay Tankha got elected on Congress ticket in Madhya Pradesh. The Bharatiya Janata Party suffered a setback in Haryana where BJP-supported independent candidate Subhash Chandra, a media baron, lost to Congress-supported independent R.K.Anand. Voting was held for 27 Rajya Sabha seats in Uttar Pradesh, Madhya Pradesh, Uttarakhand, Jharkhand, Rajasthan and Haryana on Saturday.