CHARLOTTE, N.C. -- Campaigning his way toward the Democratic National Convention, President Barack Obama slapped a "Romney doesn't care" label on his rival's health-care views Sunday and said Republicans want to repeal new protections for millions without offering a plan of their own.
Vice President Joe Biden swiftly broadened the attack, accusing Republicans of seeking to undermine the decades-old federal program millions of seniors rely on for health care. "We are for Medicare. They are for voucher care," he said.
The president and vice president campaigned separately across three battleground states as delegates descended on the Democrats' convention city for two days of partying before their first official meeting Tuesday in the Time Warner Cable Arena.
The economy is the dominant issue of the campaign, and Biden's itinerary, in particular, underscored the threat that a sluggish recovery and high, 8.3 percent unemployment pose to Democrats seeking another term in power. He was in Pennsylvania and Wisconsin, states that have received little attention previously as the candidates, their parties and outside allies concentrate on the areas of the country deemed most competitive.
Obama's convention opens with evening speeches by first lady Michelle Obama and San Antonio Mayor Julian Castro, the keynote speaker.
The president will be nominated for a new term on Wednesday, when former President Bill Clinton will speak. Biden delivers his acceptance speech the same evening.
Obama's prime-time acceptance speech, to be delivered at the outdoor Bank of America Stadium, caps the convention on Thursday night. Aides predict a capacity crowd at the site, which for football can seat nearly 74,000.
Democrats are taking their turn in the convention spotlight just days after the Republicans met in Tampa, Fla., to nominate former Massachusetts Gov. Mitt Romney for the White House and Wisconsin Rep. Paul Ryan to be vice president.
A parade of speakers in Tampa excoriated Obama's handling of the economy, which is struggling in the weakest recovery from recession of the post-World War II era.
The economy has been the top issue in opinion polls all year, and on that subject the president is eager to turn the focus onto Romney.
Republicans "will take us backwards," Obama said, to the age of "trickle-down, you're on your own" economics that begin with tax cuts for the rich but tax increases for the middle class.
The president made a brief detour to foreign policy in his speech.
"Governor Romney had nothing to say about Afghanistan this week or the plans for the 33,000 troops who will have come home from the war by the end of this month," he said.
Obama, pointing to successes, declared, "I said we'd take out bin Laden and we did." Obama's schedule Monday includes an appearance in Toledo, Ohio, another battleground state, before a trip to Louisiana to inspect damage from Hurricane Isaac.
Romney spent Sunday at his Wolfeboro, N.H., vacation home, leaving only to attend church services with his wife, Ann.