|German Chancellor Angela Merkel faces several more tests as more regional elections loom [GALLO/GETTY]
Germany's Social Democrats have won a resounding victory state election in Hamburg, according to an exit poll released hours after voting closed.
The party routed Chancellor Angela Merkel's Christian Democrats, who had controlled the state for the past 10 years - but which failed to secure even half the number of votes they scored in a 2008 poll.
"This is a very, very impressive result," Social Democrat leader Olaf Scholz told a joyous crowd of supporters.
"We will go to work now - and do serious, pragmatic and reliable politics."
The Social Democrats' 49.5 per cent of the vote, up from 34.1 per cent at the last election, will virtually secure them an absolute majority in the state legislature - with 63 of 121 seats.
"An hour of helplessness"
Merkel's Christian Democrats were quick to concede defeat after its worst ever result in Hamburg. It polled just 20.5 per cent - down from a 42.1 per cent share in 2008.
"This is a harsh defeat for Hamburg's CDU," Christoph Ahlhaus, the conservative mayor of Hamburg, said.
"It's an hour of helplessness for us."
The collapse in support for Merkel's party was blamed on local issues, including a popular longtime mayor's resignation and the dissolution of an experimental coalition with the Greens. The elections in Hamburg was the first in a series of seven regional elections which will be seen as a test of the Chancellor's conservative agenda.
The Greens, who had reportedly hoped to form a centre-left government with the Social Democrats, gained two per cent, standing at 11.5 per cent - while the pro-business Free Democrats, Merkel's junior partner in the federal government, re-entered parliament with 6.5 per cent, after being exempted for polling below the five per cent threshold in 2008.
The exit poll also predicted the Left Party scored seven per cent.
No margin of error was given for the poll, carried out by Infratest Dimap. About 1.3 million people were eligible to vote in Hamburg and the state election commission estimated turnout was around 63 per cent.