BERLIN (AP) — The front-runner to succeed Chancellor Angela Merkel in Germany's September election has apologized for a scene in which he was seen laughing in the background as the country's president delivered a statement on the devastating floods in western Germany.

Armin Laschet, the candidate of Merkel's center-right Union bloc to be Germany's next leader, is also the governor of North Rhine-Westphalia state — one of two badly hit by last week's floods. On Saturday, he visited the town of Erfstadt, which was the scene of a dramatic rescue effort after the ground gave way, with President Frank-Walter Steinmeier.

While Steinmeier gave a statement to reporters after the visit, Laschet and a group of others stood in the background. Photos showed him turning to someone else and laughing.

Lars Klingbeil, the general secretary of the center-left Social Democrats, told Sunday's Bild am Sonntag newspaper that Laschet's behavior was “lacking in decency and appalling.”

“They say that people's character shows in times of crisis,” he added.

Laschet took to Twitter on Saturday evening to explain himself and thank Steinmeier for his visit.

“The fate of those affected, which we heard about in many conversations, is important to us,” he wrote. “So I regret all the more the impression that arose from a conversational situation. That was inappropriate and I am sorry.”

The Union bloc currently leads polls ahead of the environmentalist Greens, with the Social Democrats in third place. The election is on Sept. 26.