BERLIN (AP) — A close longtime ally of Chancellor Angela Merkel has lost his job as head of her conservative bloc's parliamentary group, in a blow to her authority in her own ranks.

Lawmaker Stefan Kaufmann tweeted that Volker Kauder, who had led the parliamentary group of Merkel's Union bloc since she became chancellor in 2005, was defeated Tuesday by one of his deputies, Ralph Brinkhaus.

Tuesday's vote, which Brinkhaus won by a 125-112 margin, follows a wobbly start to Merkel's fourth government, a coalition of the Union and the center-left Social Democrats, which has squabbled persistently since it took office in March.