GERMAN Chancellor Angela Merkel’s Bavarian conservative allies have thrown their weight behind her quest for a fourth term in office.

The endorsement puts aside a long-running argument over her migrant policies as Germany prepares for a national election in September.

The show of conservative unity came as Merkel’s rivals, the centre-left Social Democrats, enjoy a strong poll boost from their surprise nomination of Martin Schulz as her challenger – a former president of the European Parliament and a relatively fresh face in national politics.

Bavaria’s Christian Social Union (CSU) has dominated its south-eastern state for decades and is traditionally an important source of national election votes for the bloc led by Merkel’s Christian Democratic Union (CDU).

Their sometimes-awkward alliance has been frayed since late 2015, with CSU leader and Bavarian governor Horst Seehofer one of the most prominent domestic critics of Merkel’s welcoming approach to migrants.

A year ago, he threatened her federal government with a lawsuit if it did not take measures to further secure the German border and reduce the influx of asylum-seekers, a threat never carried through. More recently, the CSU raised doubts about whether the parties would campaign together.

Merkel, Germany’s leader since 2005, announced her candidacy in November.

“We are going into this election campaign together,” Seehofer said yesterday after the parties’ leaders met in Munich. Under Merkel, he said, “Germany is an island of stability”.

Merkel acknowledged that the conservatives had taken their time to move past their dispute and focus on the September 24 election.

She said: “We needed time to make sure about the question of whether what we have in common is viable, and I am convinced that it’s better to take one day longer. I think we have enough time until September 24 to set out this common ground to the population.”

However, the parties still disagree on a CSU demand for an annual cap of 200,000 on the number of refugees allowed into Germany. Seehofer has insisted his party will not join the next government without a cap, a dispute that both leaders skirted.