By Paul Carrel and Alexander Ratz
LEIPZIG, Germany (Reuters) - Less than 24 hours after Angela Merkel's protegee won a statement of support from her party, Bavarian conservative leader Markus Soeder gave a barnstorming speech to the Christian Democrats (CDU) that reignited debate over who should be the next conservative chancellor candidate.
Annegret Kramp-Karrenbauer, Merkel's heir apparent, had appeared to end months of leadership speculation with a 'back me or sack me' appeal to delegates at the CDU congress on Friday - which they answered by standing to applaud her.
But in the conference hall on Saturday, Soeder had other ideas.
The burly leader of the Christian Social Union (CSU), Bavarian sister party of Merkel's CDU, entered to pumping dance music, like a champion boxer, before delivering a speech full of power and punch.
Urging the CDU and CSU to show unity, he took aim at the smaller parties that have eroded support for their alliance - the 'Union' - and fractured the political landscape.
The far-right Alternative for Germany (AfD) "doesn't want to go back to the '70s but the '30s!" he told some 1,000 delegates gathered in Leipzig, Saxony - an eastern state where the AfD sucked away CDU votes in a regional election three months ago.
He then turned his fire on the Greens, accusing them of double standards for opposing airports and air travel but taking flights to spread their pro-environment message.
Soeder, whose state is home to BMW and Volkswagen luxury brand Audi, said he supported electric cars. "But the car is not the enemy in Germany. Some people think an SUV is worse than a nuclear power station!" he said, to roars of laughter.
The speech impressed delegates, who are desperate to see a revival of the Union's fading fortunes before Merkel, 65, steps down.
The chancellor, in power since 2005, has said she will not seek office again at the next national election, due in 2021, and helped Kramp-Karrenbauer, 57, to become CDU leader with an eye on next year, when the Union will decide on its chancellor candidate.
But "AKK" has made several gaffes since taking over as CDU leader last December that have dented her popularity and raised questions about her suitability to be the next chancellor.
Soeder, who replaced the lacklustre leader Horst Seehofer as CSU leader, may have had his mind on the same prize with his 40-minute speech, which received rapturous applause.
"He certainly belongs to the shortlist," said Wolfgang Reinhart, chairman of the CDU group in the Baden-Wuerttemberg regional assembly.
A more senior CDU official, speaking on condition of anonymity, said Soeder was "worth thinking about", adding: "He made every sentence count."
No chancellor has ever come from the CSU, although Franz Josef Strauss and Edmund Stoiber of the CSU were the Union candidates in the 1980 and 2002 federal elections, respectively, which were both won by the Social Democrats.
"Third time lucky?" mused one congress delegate.
(Writing by Paul Carrel; Editing by Kevin Liffey)