DNA: Why did Sonia Gandhi leave Lok Sabha and go to Rajya Sabha?

Congress's Gandhi family's ties with UP are about to end. We are saying this because Rae Bareli was the last fort left in the politics of the Gandhi family, from where Sonia Gandhi was a Lok Sabha member. But today Sonia Gandhi has given nomination for Rajya Sabha elections from Rajasthan. In this way it has become clear that now Sonia Gandhi is not going to challenge any candidate in Rae Bareli.