For a few hours on Saturday, however, all six leaders seemed to put aside their differences to help the hurricane victims.

Several of the former presidents waved from the stage as an American flag flashed on the screen behind them, taking their seats after the national anthem.

Soon after Mr. Trump’s video was played, the former presidents returned to the stage. In brief remarks, Mr. Carter and Mr. Clinton praised Americans’ volunteerism. Mr. Obama thanked both members of the Bush family, who live in Texas, and spoke about the important work of citizens.

“Americans step up,” Mr. Obama said. “And as heartbreaking as the tragedies that took place here in Texas, and in Florida, in Puerto Rico and the U.S. Virgin Islands have been, what we’ve also seen is the spirit of America at its best.”

George W. Bush spoke last, urging viewers to donate and honoring his father.

“We really admire and love George H. W. Bush,” he said before standing behind his father, who remained seated. The former presidents then received a loud standing ovation.