A long-time rival of centrist ex-chancellor Angela Merkel within the CDU party, Merz has attacked her open-door migrant policy and drawn her ire for accepting support from the far-right AfD on the flashpoint issue in parliament.

At age 69, trained lawyer Merz boasts a strong business background -- including at investment fund BlackRock and on many corporate boards, which made him a millionaire -- but has never held a government leadership post.

Nonetheless, the combative orator seeks to project a statesman-like persona and has voiced confidence he can deal with mercurial US President Donald Trump, whom he has labelled "predictably unpredictable".

As the three-way coalition of centre-left Chancellor Olaf Scholz  floundered, Merz as head of the opposition CDU/CSU block rained withering fire on the outgoing "green-left" government.

Polls had long declared Merz -- despite lukewarm personal approval ratings -- the strong favourite to oust Scholz and bring an end to what Merz labels "three lost years" for Germany.

In a recent blistering parliament speech, Merz likened Scholz and his allies to business managers who have bankrupted a company but still ask to extend their contracts by four years.

"Do you know what the owners would say once they stopped laughing?" Merz asked mockingly. "They would politely ask you to leave the company. That's how it is in normal life."

Merz's campaign promise was to revive the ailing economy and rebuild Berlin's international standing for "a Germany we can be proud of again".

On Sunday a jubilant Merz -- eager to get going with his decades-old dream to run the country -- urged speedy talks to forge a new coalition government, warning that "the world out there is not waiting for us".

'Zero tolerance' 

Among his toughest pledges is to shut German borders to undocumented migrants, even if they seek asylum and to detain those awaiting deportation.

Merz has in the past labelled the sons of Muslim immigrants "little pashas" and accused some Ukrainian war refugees of "social welfare tourism", before later apologising.

Last month, Merz sparked high drama in parliament -- and waves of street protests -- when he pushed through a motion signalling his immigration crackdown with support from the extreme-right Alternative for Germany (AfD), breaking a long-standing taboo of never dealing with the controversial party.

In other signals of a rightward shift, Merz has vowed a "zero tolerance" law-and-order drive, to reverse marijuana legalisation, limit "woke" policies and gender-sensitive language and study a return to nuclear power.

Merz argues all this will lure voters back from the AfD. 

But he may yet have to temper some of his policies as he seeks one or more coalition partners.

Scholz during the campaign sought to portray his rival as a "hothead" and charged that his dalliance with the AfD signals he would one day rule with the far-right party -- a charge Merz strongly rejects. 

News magazine Der Spiegel has said Merz takes conflicts personally and is sometimes given to fits of anger, opining that "if Merz were a bullfighter, he would probably hold the red cloth in front of his stomach".

Hobby pilot 

Merz, who is Roman Catholic, was born on November 11, 1955, and lives among the rolling hills and forests of the Sauerland region of North Rhine-Westphalia state. 

At six foot six (198 centimetres) tall, Merz stands out in a crowd and is a licenced pilot who sometimes flies his own private jet. 

He has been married for more than 40 years to Charlotte Merz, a judge, with whom he has three adult children. 

He was elected to the European Parliament in 1989 and soon after to the Bundestag, where his mentor was the late CDU powerbroker Wolfgang Schaeuble.

After chancellor Helmut Kohl's long reign ended in a slush fund scandal, Merkel soon sidelined Merz to take over the party and went on to run Germany for 16 years.

For over a decade, Merz pursued a career in the private sector but never gave up his life-long ambition of becoming chancellor.

A free-market liberal who wants to cut corporate taxes and slash red tape to help Germany Inc, he outlined his views in a 2008 book titled "Dare More Capitalism".

Merz has sought to turn his long stint in the business world into a key selling point, said political scientist Antonios Souris of Berlin's Free University.

"He likes to flirt a little with this role of having returned to politics as an outsider, as an experienced captain of industry, not just a career politician like Scholz."

His CV and personal wealth have left Merz open to charges of being out of touch with voters -- an accusation he has rebuffed by insisting he belongs to the "upper middle class".