Support for German Chancellor Angela Merkel has risen to its highest level this year, a poll showed yesterday just four days before closely-watched elections in three states, but her conservative party has not benefited.

The Forsa poll showed Merkel, who is facing resistance at home over her open-door migrant policy, winning 50 percent of the votes in a hypothetical presidential-style election against her Social Democrat (SPD) rival Sigmar Gabriel, on 13 percent. Her rating is up two percentage points from the last poll.

However, the conservative bloc, made up of Merkel's Christian Democrats (CDU) and the Bavarian Christian Social Union (CSU), was unchanged at 35 percent. The SPD, junior partner in Merkel's ruling coalition, was down one percentage point at 23 percent. The Alternative for Germany (AfD) party, which is expected to perform well in Sunday's elections in the states of Baden-Wuerttemberg, Rhineland-Patatinate and Saxony-Anhalt, climbed one percentage point to 10 percent.

The votes are widely seen as the first electoral test for Merkel on her migration policy after a tough eight months when she has lost support over her handling of the crisis, opened up rifts in her coalition and been at odds with many EU partners.