Insisting that "people are doing better'' than they were four years ago, Angela Merkel made her

re-election pitch to a crowd of some 3,000 in a medieval town square in western Germany, a stump speech marred by a clutch of jeering anti-immigration protesters.

The chancellor was speaking late Monday at an election rally of her Christian Democratic Union in Gelnhausen, a town of just over 20,000 about 50 kilometers (31 miles) east of Frankfurt. While most were placard-waving CDU supporters, several dozen supporters of the nationalist Alternative for Germany party, or AfD, blew whistles and shouted at Merkel.

The German leader didn't acknowledge the protests in a 32-minute speech that covered the campaign themes of the

diesel scandal, her CDU's hewing to a balanced budget and pledges to increase domestic security. Yet the presence of loud demonstrators, a relative rarity during her rallies, hinted at the lingering tensions that have dogged Merkel since the refugee crisis exploded two years ago -- and the residual anger that could inject uncertainty into the Sept. 24 election outcome.