Former German Chancellor Gerhard Schröder is still widely remembered for the comment he made back in 2004 about Russian President Vladimir Putin's being a "flawless democrat."

Even then, almost 13 years ago, Putin was not necessarily known for his strict adherence to democratic principles in his country. But Schröder and Putin are still friends to this day. And now, there are reports saying that Schröder has been nominated to the supervisory board of the largest Russian oil company, Rosneft, and may be appointed to it at the end of September.

After Russia annexed Crimea in 2014, Rosneft was put on the European Union's sanction list. But this does not seem to bother the now 73-year-old Schröder. He has not yet officially confirmed his nomination, however.

Read more: German government distances itself from Schröder after Putin embrace

Longtime business dealings with Russia

Since 2005, Schröder has championed the Nord Stream Baltic Sea pipeline, which runs directly from Russia to Germany. Nord Stream AG is a subsidiary of Russia's state-owned gas supplier Gazprom. Schröder's involvement right after he was voted out of office in 2005 already provoked considerable displeasure in many quarters back then. And now, after reports of the Rosneft nomination, criticism has been harsh as well.

Schröder and Putin: longtime friends

"Shameless," said the former Green Party leader, Reinhard Bütikofer, now a member of the European Parliament. And the Ukrainian ambassador to Berlin, Andriy Melnyk, said it was morally reprehensible "for a former chancellor and a leading SPD member to be instrumentalized by the head of the Kremlin."

Advantage Merkel

"I will not comment on the professional future of the former chancellor here," Steffen Seibert, Chancellor Angela Merkel's spokesman, told DW on Monday. He does not have to; the mere news of Schröder's possible collaboration with Rosneft plays into the hands of Merkel's and her Christian Democrat Union's (CDU) election campaign.

Ex-Chancellor Schröder about to take a doubtful plunge in a caricature by Sergej Elkin

But within Schröder's party, the Social Democrats (SPD), frustration with the former chancellor is growing.

Current polls show that the SPD and its top candidate Martin Schulz are trailing far behind the CDU and the current chancellor, and there are only six weeks to go until the elections. The SPD's secretary-general, Hubertus Heil, decided to take the bull by the horns when asked about Schröder's plans, saying, "In the first place, this is Gerhard Schröder's personal decision. I do not know what he will decide. He won't let anyone tell him what to do. I only know that after his term as chancellor, Martin Schulz does not intend to work in the private sector."

"After his term as chancellor": Heil probably has little choice but to talk that way during an election campaign.

Shock and anger behind closed doors

Other top SPD members are reluctant to discuss Schröder in public, but behind closed doors, they all vent their resentment against him. They say there is despair over Schröder's "insensitivity"; after all, he once served as chairman of the SPD.

Reports of Schröder's possible job in Moscow make work for Schulz even more difficult, they say, and many SPD members express rancor at the fact that his pension as former chancellor does not seem to be enough for him.

The general tenor of their remarks is that while the party is working itself to the bone in this difficult election campaign, Schröder is coming along and stabbing them in the back.