According to poll released on Thursday by survey institute Infratest dimap, support for the German Social Democrats (SPD) dropped by two percentage points to 21 percent, compared to last week.
Support for Chancellor Angela Merkel's Christian Democratic Union (CDU) and the Christian Social Union (CSU) held steady at 37 percent.
The Left party (Linke) and Free Democratic Party (FDP) were the only parties to gain support, rising to 10 percent (Linke) and 9 percent (FDP). The right-wing populist Alternative for Germany (AfD) continues to be third strongest party with 11 percent and the Green party (Gruene) stagnated at eight percent.
Concerning the candidate for chancellorship, Merkel is seen as the stronger leader by a comfortable 75 percent of respondents in this week's survey. Although she is also seen as more competent by 63 percent, and more credible by 52 percent, her ratings have slightly fallen since July's survey.
A majority of all Germans would now choose Merkel over Schulz as chancellor. The share of those polled who favored the CDU-leader surged by five percentage points to 54 percent compared to the August 31 survey by Infratest dimap.
Support for an EU membership of Turkey fell to a historical low of 12 percent. Of 1,003 people interviewed, 84 percent think that Turkey should not be part of the EU as a "matter of principle" and 88 percent said that the German government should take a firmer stance on Turkey.
Despite this tough position, 80 percent think it is good that Merkel is signaling to Turkey that she is "ready to talk".
Concerning the diesel emission scandal in the German automotive industry, a huge majority thinks that carmakers must do more to compensate the owners of vehicles (83 percent) and that German politicians were much too forgiving and lax in their engagement with the automotive industry (79 percent).
Nevertheless, only 30 percent of respondents agree that only non-petrol and non-diesel vehicles can be registered from 2030 onwards. Support for an immediate driving ban of old diesel vehicles from cities with high air pollution has fallen by six percentage points to 42 percent.