Merkel is adamant that migrant policy can only be effectively agreed and implemented at the European level and is at loggerheads with her own conservative Bavarian allies and her Interior Minister who want unilateral action.
Merkel's welcome to refugees also infuriated Seehofer and his CSU, the sister party of her Christian Democrats in the southern state of Bavaria, which became the main entry point for most migrants. Seehofer could use his power as interior minister to enforce the Masterplan and turn away migrants at the border even without the chancellor's backing, the news agency said. "We want to finally have a sustainable solution for turning back refugees at our borders".
Seehofer and Merkel have long had an awkward relationship. The move would mean "the majority of asylum seekers who come to Europe make their way to Germany".
Seehofer, who reportedly refused Merkel's call to wait until the European summit to find a solution, is due to seek approval on Monday from CSU party leadership for his plan to turn away migrants at Germany's borders, according to reports.
Seehofer has been at odds with Merkel for a few years now, starting in 2015 when the refugee crisis began to unfold. The German Interior Ministry in Berlin said it would not "speculate" about personnel decisions.
"The people are running out of patience", he told Bild daily.
At a regular meeting of their joint Cabinets on Tuesday, Germany will seek the support of French President Emmanuel Macron to find a common European Union response for managing an influx of refugees, Merkel said Saturday in a weekly podcast.
She has pledged instead to seek bilateral agreements with arrival and transit countries and a wider solution by the European Union, which holds its next summit on June 28-29, while admitting that this plan is "ambitious".
The CSU faces a crucial state election in its home of Bavaria in October, and its hardline stance has widely been interpreted as an electioneering tactic as it attempts to claw back voters lost to the anti-immigrant Alternative für Deutschland party.
Supporters of German AfD wave flags in front of the Brandenburg Gate in Berlin, Germany, Sunday, May 27, 2018. Previously, he clashed with the chancellor on the issue of whether Islam is part of German culture, demanded that she impose limits on new arrivals, and threatened to not support her in the 2016 general election.
Seehofer plans to hold a press conference in Munich on Monday following a meeting of CSU leaders on migration, Reuters reported. The two parties govern with the center-left Social Democrats.
Macron offered his backing to Merkel, telling reporters: "Countries are committed to the paths taken by their heads of state or government".
In a sign of the frayed nerves, Germany's political and media world lurched into a brief panic Friday as several media outlets fell for a hoax tweet claiming Seehofer's CSU was quitting the coalition.