The co-leader of Germany's Greens attacked Chancellor Angela Merkel and her Christian Democrats (CDU) on Wednesday for their "1950s" stance on same-sex marriage and insistence on pursuing a disputed multi-billion euro rail project.
With less than seven months to go until a federal election in which Merkel seeks a third term in office, Cem Oezdemir told Reuters the government should stop discriminating and classifying citizens according to sexual preference.
"The CDU has to arrive in the current century. We no longer live in the 1950s," said Oezdemir, once Germany's first lawmaker with Turkish roots.
The CDU on Monday ruled out granting same-sex couples the same tax benefits as married people, as Merkel bowed to pressure from traditionalists within her party and ended an internal debate.
Support for the Greens stood at around 15 percent in recent opinion polls, up from 10.7 percent in 2009's federal election. But the party could find it hard to carve itself a role in any coalition government emerging from September's election.
Merkel's Christian Democrats are tipped to be the strongest party in the election but will likely fall short of an absolute majority, even together with current partner the Free Democrats.
Many see a grand coalition of the Christian Democrats, their Bavarian sister party the Christian Social Union, and the Social Democrats as the most likely outcome.
The Greens are seeking a coalition with the Social Democrats, and failing that, analysts suggest a deal with the CDU might be possible. But officials from both parties are sceptical they would make a pair that appeals to voters.
Thirty years after first entering the Bundestag, or lower house of parliament, the Greens are now represented in all 16 state assemblies.
They also run the coalition government in the affluent state of Baden-Wuerttemberg, where plans to revamp Stuttgart's train station by building subterranean tunnels has divided citizens and politicians and threatens to far exceed its budget.
Deutsche Bahn's supervisory board this week backed the "Stuttgart 21" project, even though it will cost at least 6.5 billion euros ($8.5 billion), 2 billion more than previous estimates.
"Merkel wanted this decision from the board. She put quite some pressure on them ... Now it's Merkel's train station. So she has to say where the money should come from, where the 2 billion euros should be saved," said Oezdemir.
If the Greens came to power in September's elections they would reconsider the project if it was not yet beyond the point of no return.
"We are in a position today where we could exit, if the will is there ... one could discuss alternatives if one wanted to," he said.
"But once the tubes have been installed for the tunnels, it will get very difficult."