Michelle Obama at the DNC: 'Don't Let Anyone Ever Tell You This Country Isn't Great'

— -- In a rousing call for Democratic unity behind Hillary Clinton, First Lady Michelle Obama described the presumptive Democratic presidential nominee as a "true public servant" with the ability and experience to lead, while criticizing Donald Trump without mentioning him by name.

"Hillary Clinton has never quit on anything in her life," Obama said. "I want someone with proven strength ... someone who understands that the issues a president faces are not black and white and cannot be boiled down to 140 characters."

"When you have the nuclear codes at your fingertips and the military in your command, you can't make snap decisions," she added. "You can't have a thin skin or tendency to lash out."

Obama's speech helped calm a convention marred by divisions between supporters of Clinton and Sen. Bernie Sanders through its first day. Earlier Monday, Rep. Debbie Wasserman Schultz, D-Florida, resigned from her role as DNC chair before the convention officially started, after hackers released thousands of emails from DNC officials that revealed efforts to undermine Sanders' campaign.

Obama cast Clinton's candidacy in historic terms, and her presidency as the natural successor to her husband's. Describing waking up every morning "in a house built by slaves," the first African-American first lady of the United States praised Clinton's efforts to "keep coming back and putting those cracks in that highest and hardest glass ceiling."

"I watch my daughters, two beautiful, intelligent, black young women, playing with their dogs on the White House lawn," Obama said. "Because of Hillary Clinton, my daughters and all our sons and daughters now take for granted that a woman can be president of the United States."

"Don't let anyone ever tell you that this country isn't great, that somehow we need to make it great again," Obama said, in a final jab at Trump. "Because this right now is the greatest country on Earth. And as my daughters prepare to set out into the world, I want a leader who is worthy of that truth."

President Obama praised his wife's speech in a Monday night tweet: