Walter Myers, 75, of Springfield, protested the event with placards, including one that said "NOBAMA." He said he's an independent who "voted for Sarah" in 2008.
Of job growth figures released Friday, Myers said, "I think it's a lie. I don't believe it's true ... I know too many people looking for jobs and can't find them."
Obama ended his day in Lima where volunteer Alice Jackson, 64, had a photo taken with the president just before he picked up her 3-month-old son in front of the stage.
"You can't top that," she said. "You couldn't have a better day."
Aside from the battle of words, there was a battle of the bands: Romney's campaign said he would be joined by southern rockers the Marshall Tucker Band on Sunday and Monday and by country music star Rodney Atkins on Sunday. Michigan native Kid Rock was the headliner for Friday night's rally.
Obama has Bruce Springsteen and rapper Jay-Z joining him Monday. The campaign said Grammy-winning singer-songwriter Jason Mraz is on the bill Sunday for stops with Vice President Joe Biden and his wife Jill in Lakewood, Fremont and Lancaster, Ohio. Motown hit-maker Stevie Wonder will be with Obama on Sunday in Cincinnati.
The music stars not only can warm up supporters in rallies, they are a good way to lure potential voters off the sidelines in the tight race.
"The benefit is that the folks who perform are likely to bring people out to the rallies, just to see them for free, who may be marginal voters," said Christopher Kelley, a Miami University political scientist. "They see the candidates alongside the performers they like and hear them talk about them; that's a good way of raising your turnout a couple of percentage points."
Associated Press writers Julie Carr Smyth in Hilliard, Ann Sanner in Springfield and John Seewer in Lima contributed to this report.
Contact the reporters at http://twitter.com/dansewell and http://twitter.com/jcarrsmyth