German Finance Minister Wolfgang Schäuble | Adam Berry/Getty Images Schäuble says German migration policy was a mistake Germany’s powerful finance minister break with Merkel on migration.

Germany's powerful finance minister, Wolfgang Schäuble, on Sunday criticized Chancellor Angela Merkel's open-door policy towards refugees.

Schäuble's remarks, which came as protests erupted across the U.S. in reaction to President Donald Trump's decision to ban the citizens from seven Muslim-majority countries from entering the Unites States, show the centrality of the issue across Europe as the Germans, French and Dutch go to the polls later this year.

"We politicians are people. We too make mistakes," Schäuble said in Germany's Welt am Sonntag, in a reference to German's migration policy. "But one can at least learn from mistakes."

Schäuble has gone up against Merkel before. In 2015, he publicly suggested that Greece leave the eurozone, saying that the country should take a "timeout."

Known for his off-the-cuff remarks, Schäuble is a frequent critic of the lack of EU unity on how to deal with the issue of refugees coming to Europe.

He has also suggested increasing taxes in Germany to invest more in countries such as Turkey and Libya as a way to curb the numbers of people arriving on European shores.

In the interview with the Welt am Sonntag, Schäuble also said that the EU should ensure that its social security systems are more evenly balanced so that refugees don't all seek residence in countries with better benefits. Such subjects have been considered "taboo" in Germany so far, he said.

His remarks come as Merkel's conservative Christian Democrats, of which Schäuble is also a member, lose ground to the anti-immigrant Alternative for Germany (AfD) party. In September last year, the AfD finished ahead of Merkel's party in local elections in the state of Mecklenburg-Vorpommern.

Immigration is also set to be a dominant theme in France's presidential election in May, especially since a series of terror attacks in Paris drew questions about the so-called Schengen Area, which allows for the free movement of people.

Although those found to be involved in the 2015 Paris attacks were French and Belgian citizens, some had traveled to either Turkey or Syria in the years prior to the attack.