The executive of Germany's center-left Social Democrats (SPD) unanimously nominated Schulz in Berlin on Sunday to become their party's chairman and chancellor candidate at a special conference due in March.

Incumbent chairman Sigmar Gabriel stepped aside last Tuesday to become foreign minister but retain his post of vice-chancellor in Merkel's grand coalition cabinet.

Merkel's run for a fourth term began Saturday, with her being nominated by conservative party members in northeastern Germany. The country will hold federal elections on September 24.

Merkel is bidding for a fourth term as chancellor

Addressing a crowd at the SPD's Berlin headquarters, ex-European Parliament President Schulz vowed equitable tax rules, European solidarity on migrant issues, and a determined campaign against terrorism based on principles of open society and prevention.

Schulz, 61, said he would fight for greater equality, improved childcare and mitigation of "deep divisions" in Germany where "hard-working people" hold society together.

It was not just when a shop cashier was sacked for a small misdemeanor while company managers received bonuses despite blunders, Schulz said, or that a backer paid his taxes while a global coffee concern parked its earnings in tax havens.

"It's important for me that the hard-working people in this country, who stick to the rules, who take care of their children and often also their parents, who sometimes despite two incomes just make ends meet, that these people and their anxieties form the focal point of our politics, " he said.

Strengthening civil society

Germany's civil society must be strengthened to defend democracy, Schulz said while rounding on the far-right Alternative for Germany (AfD), an anti-migrant, populist party that has opposition footholds in 10 of Germany's 16 regional states.

"The party of the Höcke's, Gauland's and Petry's is no alternative for Germany but instead a disgrace for Germany," said Schulz, referring to Holocaust-denial remarks made recently by Bjoern Höcke, an AfD leader in the Thuringia state assembly.

Trump's stance 'shameless'

Schulz accused US President Donald Trump of attacking minorities in the United States with "shameless and dangerous" statements. "This is a taboo breach that is intolerable."

While Germany and Europe must retain the transatlantic partnership as a fixed component of policy, they had to make it clear to Trump that international human rights also apply to him, Schulz insisted.

Referring to Hungarian Prime Minister Viktor Orban's isolationist stance toward refugees, Schulz said Orban's actions were "an affront" to European unity.

Refugees entitled to protection

Refugees fleeing wars in Africa and the Middle East had the right to protection, said Schulz while adding that the causes of flight must be tackled at source.

Referring to Germany's large intake of refugees in 2015, Schulz said EU nations that failed to show solidarity must reckon with EU funding cuts, for example, in the agricultural sector.

It was "repulsive" that "rat-catchers" had tried to make political capital on the backs of refugees, Schulz added.

Fairness pact after US debacle

Schulz said he would ask all parties contesting Germany's Bundestag parliamentary election in September to agree to a fairness pact.

"What we saw last year during the election campaign in the United States, the lack of decency in debates, that shocked me deeply," Schulz said.

"It opened up rifts and destroyed much in a country which once stood for freedom and tolerance," he added. "That mustn't happen to us in Germany."

Greater chance

Surveys since Gabriel renounced the SPD's top candidacy last Tuesday, show that Schulz has a greater chance, although small, than his fellow party member of unseating Merkel, who's running for a fourth term as chancellor.

Gabriel (L) visiting French Foreign Minister Ayrault on Saturday

Current surveys show Merkel's conservatives drawing about 34 percent voter support, with the SPD on 23 percent, the AfD on 13 percent, the Greens on 11 percent and the post-communist Left party on 10 percent.

One scenario is for a SPD/Greens/Left coalition, but at between 40 percent to 43 percent it would be insufficient to govern. Another scenario is a repeat of Merkel's right-left grand coalition.

ipj/sms (KNA, Reuters, dpa, AFP)