In a move that seems baffling at first glance, former chancellor Helmut Kohl spent the weekend welcoming Rainer Brüderle, a former economics and technology minister, and Philipp Rösler, the vice minister for economics and vice chancellor, and the leader of the Freie Demokratische Partei (FDP, Free Democratic Party), to his home — and indicating that he was all but endorsing the FDP in elections later this month.