German Chancellor Angela Merkel's preferred successor Armin Laschet of the conservative CDU/CSU bloc revealed his choice by mistake as he cast a ballot in Sunday's parliamentary polls.His incorrectly folded ballot showed that the conservative leader unsurprisingly voted for his own party at a polling station in his hometown of Aachen, where he arrived together with his wife.The blunder made social media users wonder whether Laschet had violated the national voting rules, which prohibit revealing election choices until after the polls close.But the federal returning officer made clear on Twitter that Laschet's vote would not be annulled."A nationally known politician voted, as expected, for his own party. This cannot be considered election influence ... If a ballot is folded incorrectly, the election commission offers another one. If the ballot is already in the ballot box, it can no longer be taken out and is valid," he wrote.Germans went to the polls on Sunday to elect the next parliament, which will appoint Merkel's successor. The make-up of the new government is not expected to be known immediately.