CHARLOTTE, N.C. (AP) — Democrats are using one of Barack Obama's strong suits, that voters believe he understands the problems of ordinary people, to trump his weakest suit, the economy.

Michelle Obama played those cards with force in a speech declaring that after four years as president, her husband is still the man who drove a rust-bucket on early dates, rescued a coffee table from the trash and knows the struggles of everyday Americans because he lived them in full.

"I have seen firsthand that being president doesn't change who you are, it reveals who you are," the first lady said to lusty cheers Tuesday night in a deeply personal, yet unmistakably political testimonial highlighting the Democratic National Convention's opening night.

Bill Clinton, the last president to preside over sustained economic growth and a balanced budget, gets the star turn Wednesday night in a speech placing Obama's name into nomination — a high point in a checkered relationship between two men who sparred, sometimes sharply, in the 2008 primaries, when Clinton was supporting wife Hillary's campaign for the nomination.

Republican presidential candidate Mitt Romney, the career venture capitalist, appeared nowhere in Mrs. Obama's remarks. But there was no mistaking the contrast she was drawing when she laid out certain values, "that how hard you work matters more than how much you make, that helping others means more than just getting ahead yourself."

Such subtleties were otherwise missing from the stage as speaker after speaker teed up to take a strip off Romney and the Republicans, answering the catcalls of last week's GOP convention in kind. The party's up-and-coming Julian Castro, mayor of San Antonio, Texas, captured the tone in branding Romney a millionaire "who doesn't get it." Said former Ohio Gov. Ted Strickland, "If Mitt was Santa Claus, he'd fire the reindeer and outsource the elves."

Polling gives Obama a consistent advantage over Romney as the more empathetic and in-touch leader. But the sputtering economy is the topmost voter concern and Obama's highest mountain to climb after more than 42 months of unemployment surpassing 8 percent, the longest such stretch since the end of World War II. No president since the Great Depression has been re-elected with joblessness so high.

A new report found manufacturing activity declined for a third straight month. The Treasury Department announced Tuesday that the government's debt passed $16 trillion. And the latest unemployment report, coming Friday, offers more potential fodder for Romney's case against his rival's stewardship unless it shows marked improvement. The GOP candidate took a few days' hiatus from the campaign trail, preparing in Vermont for three fall debates with Obama that could prove pivotal in this close election.

Recalling life before Washington, Mrs. Obama spoke of the "guy who'd picked me up for our dates in a car that was so rusted out, I could actually see the pavement going by through a hole in the passenger-side door." She described a marriage of kindred spirits, both from humble roots, and said the president's work on health care, college loans and more all come from that experience. "These issues aren't political" for him, she said. "They're personal."

"Barack knows what it means when a family struggles," she said. "He knows what it means to want something more for your kids and grandkids."

The first lady took the stage as the most popular figure in this year's presidential campaign. Michelle Obama earns higher favorability ratings than her husband, Romney, his wife, Ann, or either candidate for the vice presidency, according to the latest Associated Press-GfK poll. And views of Mrs. Obama tilt favorably among independents and women, two focal points in her husband's campaign for re-election.

Obama watched his wife's address back in Washington, two nights before his own convention-closing speech in the 74,000-seat Bank of America stadium, if uncertain weather permits the outdoor venue. He closed a pre-convention tour of battleground states in Norfolk, Va., dispensing a case of White House-brewed beer at a fire station and summoning a crowd at Norfolk State University to resist apathy and make sure to vote.

Republicans are "counting on you, maybe not to vote for Romney, but they're counting on you to feel discouraged," he said. "And they figure if you don't vote, then big oil will write our energy future, and insurance companies will write our health care plans, and politicians will dictate what a woman can or can't do when it comes to her own health."

Romney-bashing was the order of the night in Charlotte.

"Trust comes from transparency and Mitt Romney comes up short on both," stated Senate leader Harry Reid. The Nevada senator darkly surmised that "we can only imagine what secrets would be revealed" if the wealthy Republican candidate released years of his tax returns. But, notably, Reid dropped his unsubstantiated claim that Romney had avoided years of tax liability.

Democrats roared when the late Sen. Edward M. Kennedy was shown mocking Romney in their 1994 Senate race. "On the issue of choice, I am pro-choice, my opponent is multiple choice," the late senator said as cheers grew louder. Romney once supported abortion rights, now opposes them, and has been criticized as a flip-flopper on a number of issues.

Castro, the first Hispanic chosen to deliver a keynote address, recalled Romney's support for mandatory health insurance when he was governor of Massachusetts, and his opposition to that federal mandate in Obama's health care law. "Gov. Romney has undergone an extreme makeover, and it ain't pretty," he said.

In convention floor interviews, delegates said Obama had made a clear difference in their lives over four years.

Wisconsin delegate Kaeleen Ringberg said the president's health care law extended her insurance and student loan aid kept her debt manageable. "I just graduated from college — I'm 23 — and I can stay on my parents' health insurance for another three years while I try and make my way in the world," she said. "That has helped me a lot, brought me a lot of security. I might not get a good-paying job for a while, but at least I have my health insurance."

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Woodward reported from Washington. Associated Press writers Jennifer Agiesta and Jack Gillum in Washington, Matthew Daly in Norfolk, Va., Steve Peoples in Ohio, Kasie Hunt in Vermont, , Thomas Beaumont in Des Moines, Iowa, and Ken Thomas, Matt Michaels and Jim Kuhnhenn in Charlotte contributed.