President Obama’s appearance at a campaign event this week for presumptive Democratic presidential nominee was postponed, a White House official said Sunday.

Obama was scheduled to appear at a Clinton rally on Wednesday in Green Bay, Wisconsin. The president formally endorsed Clinton in a web video released last week.

“In light of the attack in Orlando, the President’s travel to Green Bay, Wisconsin scheduled for Wednesday has been postponed,” the official said in a statement. “We will have more information on the President’s schedule as soon as it is available.”

The mass shooting in the early morning hours on Sunday at a gay nightclub in Orlando left 50 dead and 53 injured.