BERLIN (Reuters) - Support for German Chancellor Angela Merkel's conservatives has dipped below the 30 percent mark for the first time, a poll showed on Tuesday, with her Social Democrat (SPD) coalition partners gaining slightly a year before a federal election.
The INSA survey in Bild newspaper put Merkel's conservatives down 0.5 percentage points at 29.5 percent, the lowest level measured for the bloc by that polling institute.
The SPD gained 1 percentage point but was still far behind at 22 percent and the anti-immigrant Alternative for Germany (AfD) was unchanged on 15 percent.
Merkel's popularity waned after she launched her open-door migrant policy last year, although it has recovered somewhat in the last few months. She is widely expected to stand for a fourth term in September 2017.
The AfD has gained ground in regional elections this year and pollsters say many voters are disillusioned with Merkel's right-left ruling coalition.
The SPD's preferred partner is the Green Party, down 0.5 percentage points at 11 percent. The radical Left party, which some in the SPD view as a possible partner, was up by the same amount at 12 percent.
"Germany is looking at the most exciting election in its history," INSA chief Hermann Binkert told Bild.
Other surveys show similar trends but INSA tends to show higher support for the AfD than other pollsters.
(Reporting by Madeline Chambers; Editing by Alison Williams)