FILE PHOTO: A balloon with the logo of the Social Democratic Party (SPD) is seen as Martin Schulz, top candidate of SPD for the upcoming federal election, gives a speech during an election rally at one of Bavaria's oldest fairs, the Gillamoos Fair in Abensberg, Germany, September 4, 2017. REUTERS/Michael Dalder

BERLIN (Reuters) - Chancellor Angela Merkel’s conservatives widened their lead over the Social Democrats following a television debate in which Merkel came across as more convincing and reliable than her SPD challenger Martin Schulz, a poll showed on Thursday.

The weekly survey by Infratest dimap for ARD television showed support for Merkel’s CDU/CSU bloc holding steady at 37 percent while the SPD dropped two percentage points to 21 percent - their lowest reading in the poll since early January.

The pollster questioned 1,503 voters from Monday to Wednesday, meaning the survey was the first fully conducted after Sunday’s television debate in which hardly any policy differences emerged between Merkel and Schulz.

The anti-immigration, euro-hostile AfD came in unchanged at 11 percent, making it the third-strongest political force. The radical Left followed with 10 percent, up 1 point.

The business-friendly FDP scored 9 percent, also up 1 point, while the environmental Greens were unchanged at 8 percent.

The polls indicated two parties FDP and the AfD should enter the Bundestag as they look set to beat the 5-percent threshold.

The fractured political landscape could make it hard to form a viable alliance other than the current grand coalition between Merkel’s CDU/CSU and the SPD.

Another scenario could be a tricky three-way “Jamaica” coalition between Merkel’s conservatives, the FDP and the Greens, though such a broad alliance has never been tested on the federal level before.