"The Congress President would never want to become the prime minister of the country as she wants to see her son or daughter holding the post," he said in Jaunpur on the second leg of his 'Bharat Suraksha Yatra'.
He termed Gandhi's resignation from the Lok Sabha and Chairperson of the National Advisory Council as steps taken due to "compulsion", saying she was left with no option in the wake of the office of profit controversy.
"It is wrong to call it a big sacrifice," he said. Attacking the Left parties supporting the government at the Centre, Singh said they were "mere chorus singers" with no separate identity of their own.
He accused the United Progressive Alliance government of trying to include over two crore Bangladeshi immigrants in the voters' list by providing them rations cards and warned that the BJP would "bring in a legislation to oust them" if it came to the power at the Centre.
Criticising the law and order situation, he said "the prices of commodities were spiralling but human blood was the cheapest with terrorists and criminals killing people at will.
Even the effective Prevention of Terrorist Activities Act has been done away with, giving a boost to the morale of terrorists".
The BJP chief ruled out changing the colour of the party flag. "The suggestion was discussed in detail at the party forum and was rejected," he told reporters in Bhadohi.