WASHINGTON--In 2008, Michelle Obama used the occasion of the Democratic Convention to redo her image. Four years later First Lady Michelle Obama is one of the most popular figures in the Obama administration and will kick off the opening night of the 2012 Democratic Convention on Tuesday, Sept. 4, convention officials announced Tuesday.

Mrs. Obama will speak at the Time Warner Cable Arena in Charlotte, N.C. Also on the stage the first night: San Antonio Mayor Julián Castro. He will be, according to the convention, "the first Latino keynote speaker at a Democratic National Convention."

"Having both the First Lady and Mayor Castro speak on the opening night of our convention will bring together two incredible leaders whose life stories both embody the promise of America, that if you work hard and play by the rules, you can make it," said 2012 Democratic Convention Chair, Los Angeles Mayor Antonio Villaraigosa said in a statement. "The First Lady is an inspiration to millions of Americans, and has been a tireless advocate for military families and our nation's children. As the person who knows him best, she will offer unique insights into the President as a husband, father and a leader over the last four years."

"As mayor, Julián Castro has worked tirelessly to move San Antonio forward by building its economy from the middle out, not the top down, by putting the city on a path to being a leader in the new energy economy and making innovative investments in education to prepare San Antonio's students for the jobs of the future," continued Mayor Villaraigosa. "That's the same vision forward for the middle class the President has, and it stands in stark contrast to Mitt Romney, who's ready to return us to the same policies that crashed our economy."