The German government says the head of the country’s immigration authority is stepping down for personal reasons, a move that comes as the country is struggling to cope with a flood of refugees and other migrants. The Interior Ministry said in a statement Thursday that it had accepted the resignation of Manfred Schmidt, the head of the Federal Office for Migration and Refugees. It gave no further details on Schmidt’s decision. Interior Minister Thomas de Maiziere thanked Schmidt for his “extraordinary work” at an extremely difficult time. He did not immediately announce a replacement. Germany says it is expecting some 800,000 migrants to arrive this year, with some estimates as high as 1 million — around five times last year’s total.