The Congress could be in serious trouble depending upon its response to the Election Commission’s showcause notice. In the worst case, the use of Chhattisgarh’s state-owned aircraft by Congress chief Sonia Gandhi and Chief Minister Ajit Jogi, in violation of the model code of conduct, can lead to the cancellation of the party’s election symbol. While threatening to withdraw the party’s national status, the EC had issued the notice yesterday seeking Sonia’s explanation on why she used a state-owned aircraft for election purposes in Chhattisgarh. Even as the Congress kept revising its response from ‘‘no-she-didn’t’’ to ‘‘yes-she-did’’, EC sources said the Commission would not have taken such an unprecedented step — ‘‘first of its kind’’ — before checking the records. While admitting that Sonia had used the helicopter, the Congress tried justify the action by claiming it was used by her to get to Sriperumbudur from Chennai on October 10 to receive President A.P.J. Abdul Kalam for Rajiv Gandhi’s memorial service. ‘‘It was a solemn occasion where no speeches were made. She certainly did not use it from Raipur (in Chhattisgarh) or for electioneering,’’ a Congress leader claimed. EC sources, however, said Chhattisgarh records show that the Congress president used the aircraft once but to travel to various places in Chhattisgarh from Raipur. Then it was used to go to Cuddapah and Hyderabad in Andhra Pradesh, before she went to Chennai. ‘‘The Commission’s notice was based on records obtained by it. It would not have taken such a severe step as issuing a showcause notice without verifying facts. The Chhattisgarh CM used the state aircraft for election purposes eight to nine times,’’ the sources said. Party spokesperson Abhishek Manu Singhvi said: ‘‘The Congress will be responding (to the poll-panel’s notice) in a day or two.’’ Once the EC receives the Congress reply, the full Commission will meet to take a decision ‘‘which could range from cancellation of symbol, which would be an extreme step, to passing of strictures’’ which could be embarrassing for the party. AICC general secretary Oscar Fernandes has been given the task of framing the response to EC and is reportedly consulting legal experts. Meanwhile, the BJP welcomed the EC’s showcause notice to the Congress. BJP general secretary Mukhtar Abbas Naqvi said: ‘‘There is nothing new about their violation of the code. They, in fact, follow the model code more in violation than in practice.’’ In other developments, the CPI complained to the EC about the manner in which Chief Minister Chandrababu Naidu and the TDP were misusing state machinery in the run-up to polls. The party said Naidu announced several welfare schemes in the week before dissolving the Assembly.