Former President Barack Obama said President Trump treats the presidency as "one more reality show" in his address on Day 3 of the Democratic National Convention.

"I did hope, for the sake of our country, that Donald Trump might show some interest in taking the job seriously," Obama said. "But he never did."

He urged Democrats to vote for his former vice president, Joe Biden, saying that democracy is at stake in November's presidential election.

"Do not let them take away your power. Don't let them take away your democracy," he said.

Obama spoke on Wednesday from Philadelphia, the birthplace of the Constitution, just ahead of remarks by vice presidential nominee Kamala Harris.