BERLIN (Reuters) - Chancellor Angela Merkel and her partners met to formally sign their agreement on a new “grand coalition” government on Monday and admitted it was a political necessity, not a “love match”.

At a news conference before signing the deal with the leaders of her Bavarian sister party and the centre-left Social Democrats (SPD), Merkel was asked if their stern faces boded ill for the new coalition.

“I can also look friendly,” Merkel joked, drawing laughter. She added that the “grand coalition”, Germany’s fourth and her third, faced an array of global challenges, including new trade sanctions planned by the United States.

“We need Europe, a Europe that shares the same values and that acts jointly ... to deal with many of the big problems facing humanity, beginning with climate protection to fair trade to fighting the causes of migration,” she said.

Merkel, embarking on her fourth term as chancellor, urged quick action to bridge differences among EU members on a common investment budget. She said she would travel to Paris soon to discuss with French President Emmanuel Macron his proposed eurozone reforms. [nB4N1FT02G] [nB4N1KO00V]

The new government will be sworn in Wednesday, after nearly six months of political limbo following an election that returned a fragmented parliament.

Acting SPD leader Olaf Scholz, who will head the finance ministry, said “this isn’t a love match from the get-go”, but the parties would work constructively together.

LET’S STICK TOGETHER

“In a world that is becoming more difficult ... it is essential that Europeans stick together and find and develop ways to take charge of their own future,” he said.

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Even as the three parties signed the coalition agreement, tensions were simmering both within the conservatives and between them and the SPD over issues ranging from combatting poverty to advertising for abortions.

Annegret Kramp-Karrenbauer, the new secretary general of Merkel’s Christian Democrats (CDU) on Monday chided fellow party member Jens Spahn, the incoming health minister, for comments on poverty that triggered outrage from SPD leaders.

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Spahn had told the Berliner Morgenpost newspaper that recipients of unemployment benefit were not poor because their basic needs were met. Kramp-Karrenbauer said politicians with higher incomes should not presume to understand the plight of those on welfare.

Spahn sits on the CDU’s right wing, while Kramp-Karrenbauer is a centrist in Merkel’s mould. Both are seen as her possible successor.

Merkel was forced to negotiate a deal with the SPD after the failure of her attempts to form a three-way alliance with two smaller parties.

Both the mainstream political blocs suffered their worst post-war election results in the September election. Frustration about the influx of more than a million migrants since 2015 propelled the far-right Alternative for Germany (AfD) into parliament for the first time.

AfD leader Alexander Gauland told reporters his party was already reshaping politics.

“Spahn would not have become minister if his views weren’t resonating in the CDU,” he said, adding that the election results had spurred Merkel to listen to critical voices in her party. “And this new insight is thanks to the fact that the AfD has such a great result in the election.”

Kramp-Karrenbauer said the two blocs would strive for “constructive” cooperation, but criticised efforts by the SPD to reverse a ban on abortion advertising.