BERLIN — Germany’s chaos-wracked Social Democrats have named Andrea Nahles as their designated next leader, meaning women will soon be in the driver’s seats of the two biggest parties and shifting a long-skewed gender balance in politics. Alongside Chancellor Angela Merkel, Nahles is set to join a growing band of women heading, or co-leading, German political parties despite the fact that female lawmakers still account for fewer than one third of seats in parliament. Merkel has also pledged for the first time, following the lead of France and Canada, to place women in half of the cabinet posts in her fourth-term government, which is expected to be launched in late March. When Martin Schulz, the luckless former head of the Social Democrats (SPD), said last week he wanted to hand over the post to Nahles, he declared that it was time, at last, “for a woman to lead the 153-year-old party”. The election loser also said he wanted to become foreign minister, sparking an SPD outcry about his perceived opportunism that forced him to back off and has now ended his short career near the top of German politics. With the SPD in open turmoil, said the Sueddeutsche Zeitung, a major party has once again asked a “rubble woman” to clean up the mess — a reference to the mythologized women who after World War II helped clear Germany’s bombed cities. The move evoked the start of Merkel’s rise within the Christian Democrats, it said, when the East German outsider took the helm of the male-dominated conservatives as they were reeling from a campaign finance scandal around former chancellor Helmut Kohl. “When everything is in ruins,” the newspaper said, “women are asked to step in.” Nahles, 47, a former labor minister who once headed the SPD youth wing, has earned a reputation as hard-working, pragmatic and combative. She invigorated her demoralized party with a lectern-thumping speech in January, when the tabloid-