BERLIN — Germany will likely hold a federal election on September 22 next year, a government source told AFP on Wednesday, after the majority of the country's 16 states agreed on that date.

The interior ministry would inform the political parties of the states' choice next week, the source added. The official date must be cleared by German President Joachim Gauck after a decision in cabinet.

The Die Zeit weekly said the parties and cabinet were likely to agree on Sunday, September 22.

The election will pit Conservative Chancellor Angela Merkel, named by Forbes magazine as the world's most powerful woman for six of the past seven years, against former Finance Minister Peer Steinbrueck from the centre-left Social Democrats (SPD).

A poll for Stern Magazine and RTL television on Wednesday put Merkel's Christian Democrats and their Bavarian sister party, the Christian Social Union, at 37 percent and the SPD at 26 percent.

Merkel's current coalition partners, the business-friendly Free Democrats that propelled her to power in 2009, have plunged in the polls and are now at four percent, not enough to win parliamentary seats.

The ecologist Greens, with 16 percent, are the preferred coalition partners of the SPD.

Other parties in the running are the far-left Linke (8 percent in the Stern/RTL poll) and the upstart Pirate Party, campaigning for Internet freedom, with four percent.

The most likely outcome is a third term for Merkel at the head of a CDU-led coalition, but her partner is less clear.

One option is a "Grand Coalition" of CDU and SPD, similar to that which governed Europe's top economy from 2005 to 2009.

Other possibilities include an SPD-Green coalition or even, much less likely, an alliance between the CDU and the Greens.