Since Christmas, support for the liberal pro-business Free Democratic Party (FDP) nationwide had halved from 4 to 2 percent, said the research institute Forsa Wednesday.

It conducted its survey for the private RTL television network among 1,503 voters last week, just before an FDP party conference in Stuttgart where Rösler's leadership was under scrutiny.

The tabloid Bild added Wednesday that Rösler's party presidium colleague Dirk Niebel, who is also Germany's development aid minister, was facing internal party fury for publicly suggesting a leadership change at the Stuttgart conference.

Niebel under fire

Party leaders were "stinksauer" with Niebel, said Bild, using a German-language expression equivalent to "pissed off" and adding that he was at risk of losing his presidium post.

Niebel, a former FDP general secretary, is the lead candidate for FDP's southern Baden-Württemberg branch for Germany's federal election due in late September.

The general-secretary of FDP's Baden-Württemburg branch, Gabriele Heise, said of Niebel's remarks in Stuttgart last Sunday: "It was not the right moment, nor the right place, to exercise criticism."

CDU's McAllister hopeful

Lower Saxony's premier David McAllister, who is a senior member of Merkel's Christian Democrat conservatives, said Wednesday he still had hopes that Rösler and other northern German FDP candidates would re-enter the Lower Saxony parliament in Hanover on January 20.

With the FDP polling locally on four percent, it could still clear the five percent electoral law threshold, said McAllister. "I'm sure that the Lower Saxony FDP will make it."

Watch video 03:35 Germany's election year gathers pace

Rösler is currently German vice chancellor and economy minister in Merkel's center-right federal government, whose party composition closely resembles McAllister's CDU-FDP coalition in Hanover.

Forsa's chief pollster, Manfred Güllner, told the magazine Stern that half of the voters, who at the last federal election in 2009 handed the FDP a 14.6 percent return nationwide, would opt next September instead for Merkel's conservative alliance comprising her Christian Democrats (CDU) and allied Bavarian Christian Social Union (CSU).

The trend had already elevated the conservatives to 42 percent, the highest level recorded since Merkel became chancellor in 2005, said Forsa.

Opposition Greens benefit

The survey put the center-left Social Democratic Party (SPD) – Merkel's largest challenger – down 2 percent on 25 percent. Güllner attributed that decline to voter irritation, primarily over a suggestion from leading SPD candidate Peer Steinbrück last week that the chancellor's salary was insufficient.

Disappointed SPD voters were switching instead to the Green party and the communist-leaning Left Party, said Forsa. That trend had boosted the ecologist Greens to 15 percent, with the Left on 9 percent.

Visiting Weimar on Wednesday, the Greens' federal parliamentary group leader Jürgen Trittin said despite the SPD decline, the Greens and SPD still had enough votes jointly to replace Merkel's center-right coalition in September.

The Pirate party, which in 2011 became an upstart on the German political scene, still languishes around 3 percent.

In a separate survey by the pollster Infratest-dimap for Bavaria, which holds its own regional state election in September, the Rösler's FDP scored only 3 percent. It is also a junior partner, alongside Bavaria's governing CSU, which scored 47 percent, according to Infratest-dimap in its survey for BR Bavarian public broadcasting published Wednesday.

ipj/dr (dpa, AFP, Reuters)