After UPA chairperson Sonia Gandhi was elected leader of the Congress Parliamentary Party (CPP), party President Rahul Gandhi said under her leadership the Congress will prove to be a strong opposition."Congratulations to Sonia Gandhi on being elected Leader of the Congress Parliamentary Party. Under her leadership, the Congress will prove to be a strong and effective opposition party, that will fight to defend the Constitution of India," Rahul Gandhi said in a tweet.His remarks came soon after Sonia Gandhi was elected as CPP leader unanimously as the newly-elected Lok Sabha members of the party elected her to the post once again during their first meeting here on Saturday.The CPP met here at the central hall of Parliament, amid continuing upheaval in the party as Rahul Gandhi has been adamant on stepping down following a huge debacle in last month's Lok Sabha polls.However, suspense over the Leader of Congress in Lok Sabha continued as the party has authorised Sonia Gandhi to decide on it.Sonia Gandhi won the Rae Bareli seat from Uttar Pradesh by defeating the BJP's Dinesh Pratap Singh by over 1.67 lakh votes.According to party leaders, Sonia Gandhi's name was proposed by former Prime Minister Manmohan Singh.Sonia Gandhi was party president till 2017 for 19 long years before passing the baton to son Rahul Gandhi.