Even as their European partners have expressed displeasure with a more centralized European Union and the threat of increased immigration from hundreds of thousands of migrants fleeing conflict and poverty in the Middle East and Africa, Germans have largely tended to support stability at the ballot box. In March, voters in Saarland, Germany’s smallest state, returned Ms. Merkel’s center-right party to power with 40.7 percent of the vote.
This was the first indication that her main rival, Martin Schulz, a former European Parliament president, may not have the staying power though to the fall, despite capturing widespread attention and driving support for the Social Democrats to surge above the Christian Democrats at the start of the year.
The latest polls show Ms. Merkel’s party leading the Social Democrats by about eight points as the chancellor begins campaigning for her fourth term in office.
The nationalist, populist Alternative for Germany is uncertain of passing the 5 percent threshold needed to make it into the state legislature in Schleswig-Holstein. Failure to do so would send a signal that the upstart party — which rode a wave of anger and uncertainty over Ms. Merkel’s decision to take in nearly one million refugees to unprecedented popularity in several eastern states last year — is weakened as it heads into the national campaign.
The issue of immigration featured only marginally in the state, where education, traffic and the expansion of wind power dominated the debate. Torsten Albig, 53, of the Social Democrats has led a coalition of SPD, Greens and a local Danish minority party there since 2012.
His center-right challenger, Daniel Guenther, is 10 years younger and has been an energetic opposition leader, sparking debates in recent years with populist proposals that touch on voters’ fears of a growing influence of Islam on public life, such as ensuring that schools serve pork in their…