Support for Germany's Social Democratic Party, a junior partner in Chancellor Angela Merkel's coalition, has slumped to a record low, a poll showed on Saturday, piling more pressure on it to quit the government and rebuild in opposition.

There is rising skepticism that Merkel's coalition will survive until 2021 after SPD leader Andrea Nahles quit two weeks ago in the wake of her party's losses in European Parliament elections and a regional vote in the state of Bremen.

The troubled center-left SPD had the backing of 11 percent of respondents in a Forsa poll, a decline of one point from a week ago. It marked its lowest level of support since 1949 and placed it in fourth, behind the far-right Alternative for Germany (AfD) on 13 percent.