His comments to the hard-right Alternative for Germany party escalated efforts by the billionaire to influence the country’s election for chancellor next month.

Responding to the killing of a child, the poll-leading Christian Democrats are pushing to overhaul migration laws — possibly with votes from the Alternative for Germany.

The leader of the anti-immigrant Freedom Party of Austria, founded by former Nazis in the 1950s, was expected to be asked to enter into talks to form a new government.

The world’s richest man, a key adviser to President-elect Donald J. Trump, ridicules critics over his backing of the German extremist party AfD, as Germany prepares for elections.

The authorities said they were struggling to understand the motives behind ramming a car into a Christmas market in the eastern city of Magdeburg, which left a 9-year-old boy among the five dead.