PHILADELPHIA-- Michelle Obama condemned "the hateful language that we hear from public figures on TV" in her speech on the opening night of the Democratic National Convention on Monday.
"Don't let anyone tell you that America isn't great. This right now is the greatest country on earth," the first lady said.
Obama took the stage at the Wells Fargo Arena in Philadelphia facing a dual challenge: making the case for Hillary Clinton and defending her husband's legacy.
"Our motto is, when they go low, we go high," the first lady said, in a hardly-veiled shot at Republican nominee Donald Trump.
She began discussing watching her daughters grow up in the White House -- saying she remembers watching them go off to school for the first time.
"At that moment, I realized that our time in the White House would form the foundation for who they would become, and how we managed this experience could truly make or break them," she said.
She added: "This election -- every election -- is about who will have the power to shape our children for the next four or eight years of our lives. And I am here tonight because in this election, there is only one person who I trust with that responsibility -- only one person who I believe is truly qualified to be President of the United States. And that is our friend, Hillary Clinton."
Obama told the electrified audience that "we are always stronger together," saying she wants a president "who will teach our children that everyone in this country matters."
"I am here tonight because I know that that is the kind of president that Hillary Clinton will be, and that's why in this election, I'm with her," Obama said.
In a nod to Clinton's historic status as the first female presumptive nominee of a major US political party, she 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."
She called Clinton "a leader who will be guided every day by the love and hope and impossibly big dreams that we all have for our children."
Ahead of the first lady's speech, a White House official familiar with her remarks said Obama will focus on the role a president plays in the lives of children by "shaping their values and aspirations" and "why she believes Hillary Clinton is the leader with the character, temperament, and experience to best fill that role."
Temperament and experience is something Michelle Obama has been referencing a lot these days -- dipping her toe into 2016 politics by taking veiled shots at Donald Trump in speeches over the past few months.
"Right now, when we're hearing so much disturbing and hateful rhetoric, it is so important to remember that our diversity has been -- and will always be -- our greatest source of strength and pride here in the United States," Mrs. Obama said at a Nowruz celebration at the White House in April.
A White House official says Mrs. Obama tonight will talk about the values of the nation -- "opportunity, equality, inclusion" -- similar themes she's been bringing to her speeches as first lady.
"Here in America, we don't give in to our fears. We don't build up walls to keep people out," she said during a commencement address at City College of New York this June.
Michelle Obama is seen as having a unique and essential role to play for Hillary Clinton, key to keeping the Obama coalition of women, African Americans, Hispanics and young people engaged.
The first lady could turn into a powerful surrogate to boost the presumptive Democratic nominee, with her high favorability ratings.
"I think Hillary Clinton is a phenomenal woman," Michelle Obama said when asked about her at a White House event in April, "And I've gotten to know her, and I think she's made some pretty major contributions over the course of her life."
But Obama will hit the stage tonight to make the case for a woman she hasn't always supported.
During the bruising 2008 Democratic primary fight, Michelle Obama often took veiled swipes at her husband's opponent.
"They said there was an inevitable candidate, that there was someone who was going to make this race virtually impossible. And I thought, wow, it's over already?" Obama said in an interview with CBS in the fall of 2007, in the throes of the Democratic primary.
"So, our view is that if you can't run your own house, you certainly can't run the White House," Michelle Obama said from the campaign trail in the early state of Iowa in August of 2007.
But theirs was a relationship that grew once the campaign came to a close.
Shortly after Hillary Clinton suspended her campaign and endorsed then-Sen. Barack Obama, Michelle praised Clinton for the way she came around to supporting her husband.
"From the minute after this was done, right, she has always been just cordial and open. I've called her. I've talked to her. She's given me advice about the kids," Obama told Larry King in October of 2008, "We've talked at length about this kind of stuff, how you feel, how you react. She has been amazing. She is a real pro and a woman with character."
The convention stage is a platform that Obama is familiar with by now, delivering high-profile speeches in both the 2008 and 2012 conventions for her husband, speeches that drew heavily on the Obama family's personal story.
"Every step of the way since that clear day, February, 19 months ago, when, with little more than our faith in each other and a hunger for change, we joined my husband, Barack Obama, on the improbable journey that has led us to this moment," Mrs. Obama said in Denver at the DNC in 2008. "But each of us comes here also by way of our own improbable journey."
She hit similar themes, weaving in their personal narrative, four years later.
"Barack knows the American Dream because he's lived it and he wants everyone in this country to have that same opportunity, no matter who we are, or where we're from, or what we look like, or who we love," she said in 2012 in Charlotte.