Germany's government is struggling to agree on how it should deal with undocumented migrants entering the country.
A dispute between Chancellor Angela Merkel and one of her ministers could cause her fragile coalition to splinter and possibly even force her out of power.
Interior Minister Horst Seehofer wants to impose new rules along Germany's border.
His plan would allow police to turn away migrants who have already sought asylum in another EU nation.
Migrants have to apply for asylum in the first country they set foot in. But Merkel rejected that plan, saying it would only put more pressure on southern neighbors like Italy and Greece.
Her open-door policy has received intense backlash and is often credited for the rise of Alternative for Germany, a far-right, anti-immigrant party. If the dispute continues, Seehofer's party could leave the governing coalition or cause a confidence vote in Merkel.
The coalition was formed in March after extensive negotiations that lasted months.