BERLIN - The Christian Social Union (CSU), local sister party of Chancellor Angela Merkel's Christian Democrats (CDU), won an absolute majority in Sunday's state election in Bavaria, exit polls showed.

Exit polls by the ARD television and ZDF television both showed the CSU won 49 percent of votes Sunday, enough to win an absolute majority in the state legislature. The main opposition party the Social Democrats (SPD) trailed far behind with about 21 percent.

However, the pro-business Free Democrats (FDP), current coalition partner of the CSU in the state government, failed to reach the 5 percent support required to remain in the state legislature with only 3 percent support.

Sunday's election was an important test before the September 22 federal election when Merkel seeks to win a third term as chancellor. Preliminary results of the state election will be published at about 11 p.m. local time.

Victory by the CSU, led by State Premier Horst Seehofer, in the heavily-populated German economic powerhouse will give Merkel a boost as the country goes to the polls one week later. The party has governed Bavaria for 56 years but lost an absolute majority in the state legislature five years ago.

On the national level, Merkel's junior ruling partner the FDP party also struggles at the threshold of 5-percent minimum support for entering into the lower house of  federal parliament.

Polls have been suggesting Merkel will win a third term in the federal election. However, it remains unclear whether Merkel's ruling coalition will survive the election even though her CDU and the CSU maintain a double-digit advantage over chief election rival Peer Steinbrueck's SPD in opinion polls.

Should the FDP fails to garner 5 percent of votes in the federal election, Merkel may be forced to form a coalition with the SPD.