Pistorius, 64, has managed the impressive feat of becoming the most liked politician in the country while serving in Scholz's rowdy three-way coalition that broke apart last week.

While Scholz's ratings have nosedived, Pistorius' approval has soared despite steering the defence ministry, a tricky portfolio that had turned into a career graveyard for some of his predecessors.

Many voters praise his straight-talking and hands-on approach to rebuild a ramshackle armed forces and his backing for Ukraine against Russia, with Berlin the second-largest arms supplier after Washington.

German voters are set to head back to the polling booths on February 23, after Scholz's government imploded following months of internal bickering.

Scholz, 66, seems determined to stay at the helm of the Social Democratic Party (SPD), despite its current poll rating of around 15 percent.

The Spiegel magazine this week bluntly called Scholz "the wrong candidate for chancellor" and said the SPD "needs a 'game change' moment".

Rebels in the party think Pistorius could be the man to provide it.

Several regional SPD politicians have openly called for Pistorius to replace Scholz at the top of the party ticket.

Embarrassingly for the chancellor, they include two members of the state legislature in Hamburg, the northern city of which Scholz used to be mayor.

- Loyal soldier -

At first sight Scholz and Pistorius seem quite similar -- both are men in their 60s, born in the city of Osnabrueck, and trained lawyers who rose through the ranks to national politics, where they are on SPD's right flank.

Crucially, however, Pistorius managed to stay above the nasty infighting between the SPD, Greens and Free Democrats (FDP) which made up the collapsed coalition.

He has visited soldiers on bases and displayed touches of humour that contrast with Scholz's bland and technocratic style.

However so far, Pistorius has played the loyal soldier and joined the rest of the SPD leadership troops in closing ranks behind Scholz.

"We have a chancellor, and he is the designated candidate for chancellor," Pistorius said Monday. "I don't see anyone in the party who wants to change that."

The SPD's leader in parliament Rolf Muetzenich nonetheless admitted this week that there were "rumblings" of doubt within the party about Scholz's candidacy.

- No 'Messiah effect' -

Ursula Muench, director of the Academy for Political Education, said that while the SPD could hope for "a somewhat better result" under Pistorius, it's "extremely unlikely that this would result in a total turnaround of the the trend and an SPD victory".

In any case, Muench told AFP, she sees only a "slim chance" of any change at the top of the SPD for now, as Scholz looks unlikely to step aside.

While Pistorius is popular among the general public, his staunch defence of military aid to Ukraine and his talk of making sure Germany is "able to fight a war" have not endeared him to all in the SPD.

The party's left wing is strongly imbued in the pacifist tradition which emerged as a reaction to the horrors of Nazism and during the Cold War.

Muench also said there is no guarantee that Pistorius's current favourable poll numbers would survive a bruising election campaign.

"Not that much is known about Pistorius," Muench said. "Aside from defence policy not that many voters would be able to say what he stands for."

Not for nothing did SPD chairman Lars Klingbeil say last week: "I don't believe in any Messiah effect."

In the meantime the Social Democrats' rivals are gloating over its predicament.

FDP deputy leader Wolfgang Kubicki said he was happy Scholz was still leading the SPD "because I don't want the Social Democrats to improve in the polls".

For good measure, he added that a campaign battle against Pistorius "would be a real challenge".