WASHINGTON (AP) - Edging into a broader policy role, Michelle Obama is joining President Barack Obama's efforts to get the United States on track to have the highest percentage of college graduates by 2020. Mrs. Obama will speak to student's Tuesday at a high school just a few miles from the White House. Officials say the event is part of what will be a broader focus for the first lady on getting students - especially those in underserved communities - on track to attend college. According to excerpts released ahead of her speech, the first lady will tell students that meeting the 2020 goal "is going to take young people like all of you across this country stepping up and taking control of your education." The first lady will also draw on her experience as she seeks to encourage lower income students to attend college. Mrs. Obama grew up in a working class family in Chicago and went on to Princeton University and Harvard Law School. "I'm here today because I want you to know that my story can be your story," she says in the excerpts. The details might be a little different, but so many of the challenges and triumphs will be just the same. Officials said Mrs. Obama is coordinating with Education Secretary Arne Duncan, who has been overseeing the president's efforts to boost the nation's college graduation rate. The president has cited statistics showing that the U.S. ranks 12th globally in the proportion of people who hold college degrees. This new endeavor marks a slight but noticeable shift in emphasis for Mrs. Obama. While she frequently touts the value of education while speaking to students, she rarely connects those general comments with specific policy goals promoted by her husband.