U.S. first lady Michelle Obama is set to make the case for her husband's re-election Tuesday as Democrats open their national convention to nominate President Barack Obama for a second White House term.

Mrs. Obama is the headline speaker on the opening night of the three-day Democratic National Convention in Charlotte, North Carolina. Party officials say she 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.

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. The president recounted his version of the Republican gathering.

“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.

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

The party staged a pre-convention festival Monday in downtown Charlotte that featured Grammy-nominated R&B singer Janelle Monae and Oscar-winning actor Jeff Bridges.

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