Friedrich Merz’s party won Germany’s national election in late February. After weeks of coalition negotiations, Mr. Merz finally made it to the chancellor’s office late Tuesday afternoon, one failed parliamentary vote and several hours behind schedule.

In the interim, nearly all of Mr. Merz’s problems got worse.

Forecasts for the stalled German economy, which Mr. Merz has promised to jump-start, have sagged under the weight of President Trump’s tariffs and trade war. Relations with Mr. Trump’s administration continue to fray.

The far-right political party that many of Mr. Trump’s team seem to favor, the Alternative for Germany, or AfD, has pulled even with Mr. Merz’s center-right Christian Democrats in most polls. If the national election had been held again on Sunday, the AfD might have come in first, even though German intelligence has formally declared it an extremist group.

Tuesday brought the biggest setback yet. Mr. Merz failed to secure the votes to become chancellor on the first ballot in Parliament. Some 18 members of his governing coalition declined to back him. It was a first for modern Germany and a bruise for Mr. Merz, even though he came back to win the job in a second vote in the afternoon.

Mr. Merz already faced towering twin tasks as chancellor. He must show Europe and the world that Germany is ready to assume a leadership role unseen since the heyday of former Chancellor Angela Merkel more than a decade ago. He must also convince a German public that is frustrated with grinding, business-as-usual politics that mainstream parties can deliver needed change.