Germany's ruling coalition has agreed to back Foreign Minister Frank-Walter Steinmeier as the country's next president, party sources said Monday.

Chancellor Angela Merkel's Christian Democratic Union (CDU) offered its support to the country's most popular politician, Steinmeier, whose name had been put forward by his Social Democratic Party (SPD), followed by Bavaria's Christian Social Union (CSU).

"Now it's official," a CSU party source told AFP.