Michelle Obama hailed Hillary Clinton as a lifelong public servant, and slammed Donald Trump without saying his name in her speech at the Democratic National Convention, sparking calls on social media for the first lady to one day launch a presidential campaign of her own.

The first lady targeted Trump's divisive policies and outspoken presence on social media, while presenting Clinton as a more inclusive, unifying option as president.

"When they go low, we go high," she told the Democratic National Convention in Philadelphia.

Obama did not name Trump at any point during her 14-minute speech, but she did offer up several references to his campaign. "Don't let anyone ever tell you that this country isn't great, that somehow we need to make it great again, because this right now is the greatest country on Earth!" She also indirectly condemned Trump for chasing "fame and fortune."

Obama spoke glowingly about Clinton's public service record, her steadiness under public criticism, and her refusal to give up on presidential aspirations after losing the 2008 Democratic primary to Barack Obama.

"Hillary Clinton has never quit on anything in her life," Michelle Obama said. "Hillary did not pack up and go home (in 2008), because as a true public servant Hillary knows that this is so much bigger than her own desires and disappointments."

She also praised Clinton for taking on the "highest and hardest glass ceiling," in attempting to become the first female president of the United States. "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," she said.

The first lady touched on a number of recent tragedies that have hit the United States, including the shooting at a gay nightclub in Orlando, and the outrage over violence between police and African-Americans. "When crisis hits, we don't turn against each other," she said. "We listen to each other, we lean on each other, because we are always stronger together."

Obama contrasted Clinton with Donald Trump, in a veiled attack on the Republican nominee’s bombastic, frequently all-capital-letter messages on Twitter.

"The issues a president faces are not black and white and cannot be boiled down to 140 characters," she said. She also targeted Trump for his habit of speaking off-the-cuff on complex social issues.

"When you have the nuclear codes at your fingertips and the military in your command, you can't make snap decisions," she said. "You can't have a thin skin or a tendency to lash out. You need to be steady and measured and well-informed."

Social media praise for Obama

Michelle Obama's speech sparked a flurry of support on Twitter, with some saying they'll miss her as first lady, while others called for her to launch a presidential campaign of her own.

Several Twitter users took the opportunity to attack Donald Trump's wife, Melania, over her speech at the Republican National Convention last week. Melania Trump's speech appeared to borrow several lines from a 2008 address by Michelle Obama, when her husband won the presidential nomination.

People joked that Michelle Obama's speech could reappear at some point in the future for Melania Trump's own purposes.