Immigration is still a top concern for many German voters after more than a million asylum seekers entered the country over the past two years, but other issues such as income inequality, climate change and an aging population are equally divisive.
Here's how Germany stacks up against its European neighbors on these issues, and what Merkel and Schulz plan to do about them.
At 4%, Germany has a very low rate of unemployment.
And it's been falling fairly consistently -- from a high of 11.5% -- since 2005.
But although the number of full-time jobs has risen, there's been a bigger increase in the number of part-time and low-paid jobs. According to the Federal Employment Office
, 4.7 million Germans rely solely on so-called "mini-jobs," which tend to be lower paying and insecure.
Schulz has promised to crack down on precarious forms of employment, pledging to offer workers a way into more secure jobs.
Merkel has herself hired several employees from her own government office to work as "mini-jobbers" on her election campaign -- for which she has been widely criticized -- but wants to see workers in these jobs benefit from the same wage increases as regular employees.
When asked about the hirings at a news conference, she said she saw no problem with employing people on these contracts.