U.S. first lady Michelle Obama will be the highlight of the 2012 Democratic Convention's opening day, as the party aims to give a significant boost to the reelection campaign of President Barack Obama.

Party officials say her speech late Tuesday will present a behind-the-scenes look at the Obamas' life in the White House. In addition, she plans to recount how the president's early background — and his relatives' employment setbacks — helped shape his governing policies as president.

The convention's opening day appeared to reach out to women voters. Women still earn just 77 cents for every dollar men make in the U.S., and among the speakers was Lilly Ledbetter, a woman who lost her fight for equal pay in the Supreme Court but later became the namesake of the Lilly Ledbetter Fair Pay Act. President Obama signed the bill into law, giving women and other minorities more time to file a lawsuit against pay discrimination.

“This fight became bigger than Lilly Ledbetter. Today, it's about my daughter. It's about my granddaughter. It's about women and men. It's about families.”

Julian Castro, the mayor of the southwestern city of San Antonio, Texas, is giving the convention's keynote address ahead of Mrs. Obama. He is a rising Hispanic figure in the Democratic party.

Florida Congresswoman Debbie Wasserman Schultz called the convention to order Tuesday in Charlotte, North Carolina, calling it the biggest, most diverse and most open in the party's long history.

“Your participation in this convention is a testament to the fact that we are also the most vibrant, inclusive and energized political party.”

Mr. Obama told a campaign rally at a college in Norfolk, Virginia, that his Republican challenger, Mitt Romney, “did not offer a single new idea” at last week's Republican National Convention about restoring the U.S. economy.

“First of all, everything's bad. And it's Obama's fault. And Governor Romney knows the secret to creating jobs and growing the economy. The only problem was, he kept it secret. There was a lot of talk about hard truths and bold choices. But they never bothered to tell you what they were.”

Former president Bill Clinton will formally place Mr. Obama's name up for nomination on Wednesday night. Mr. Obama will accept his nomination Thursday night during a nationally-televised speech held at the city's 74,000-seat outdoor football stadium, as will his running mate, Vice President Joe Biden.

The November 6 presidential election pits Mr. Obama against Republican nominee Romney. Recent voter surveys show the two are virtually tied.