A fall in support and a government row over the refugee crisis raised the heat on German Chancellor Angela Merkel on Wednesday, forcing allies to defend the integrity of her coalition.
Germany, a favoured destination for refugees, expects 800,000 to a million new arrivals this year. Many Germans feel the country cannot cope with the record influx.
As tempers frayed, Merkel's conservatives met fierce resistance from their Social Democrat (SPD) coalition partners over plans for transit zones at border crossings to process refugees' asylum requests. They have had to deny such centres would resemble concentration camps.
Asked whether the transit zone row heralded the end of the ruling coalition, Bavarian Interior Minister Joachim Herrmann told Deutschlandfunk radio: "No! We shouldn't talk about the failure of the coalition every time (there is an argument)."
Merkel is trying to steer a course between pressure from her conservatives - especially the Bavarian Christian Social Union (CSU), sister party of her Christian Democrats (CDU) - to take a harder line on refugees and SPD opposition to the transit zones.
Bavaria is the first point of entry for many refugees and the state has threatened to take the government to court unless it tries to limit the flow of asylum-seekers.
The CDU-run Interior Ministry has drawn up a draft bill that provides for the transit zones, which would hold refugees at border crossings so asylum requests can be examined before they are allowed in.
SPD leader Sigmar Gabriel has dubbed the centres "detention zones". Responding to such criticism, CSU lawmaker Stephan Mayer told Deutschlandfunk on Tuesday: "This is not about concentration camps."
Merkel also faces increased pressure from her own conservatives to end the open-door policy she has pursued with the catchphrase: "We can do this!"
Finance Minister Wolfgang Schaeuble on Tuesday questioned whether all refugees should receive the same benefits as others in Germany.
"If we pay out from the first day as much Hartz IV (benefits) to such people - who we first need to teach to speak and write the (German) language - as to someone who has worked for 30 years and is now unemployed, what will a trade unionist say to his members?" he asked.
At a meeting of the conservatives' parliamentary group on Tuesday, Merkel resisted pressure to tighten border controls and turn away refugees arriving via Austria.
"Her dominance over the party has suffered a bit," said Gero Neugebauer, political scientist at Berlin's Free University.
But he added that she could afford to stand firm. "There is no one else who is ready to be chancellor," he said. "That is Merkel's strength."