"It was a rerun. We'd seen it before. You might as well have watched it on a black-and-white TV," Obama said.
Romney, at Cincinnati's Union Terminal, gave a retooled campaign speech with a nod to the start of college football season and a focus on creating jobs. "If you have a coach that's zero and 23 million, you say it's time to get a new coach. It's time for America to see a winning season again, and we're going to bring it to them."
Obama, as his party's faithful began streaming to Charlotte, N.C., for this week's convention, assailed Romney's three-day gathering in Tampa, Fla., as lacking any new ideas to help voters struggling with an economy saddled with an unemployment rate of 8.3 percent.
"There was a lot of talk about hard truths and bold choices, but nobody ever actually bothered to tell you what they were," Obama said. "And when Gov. Romney had his chance to let you in on his secret, he did not offer a single new idea, just retreads of the same old policies that have been sticking it to the middle class for years."
Both men were campaigning across the country as the race entered September, each day adding to the sense of urgency in a presidential contest that has remained tight since Romney sewed up the nomination in April. They recognize that undecided voters, including those in about eight key states, will begin to fully assess their options through the conventions and the upcoming debates in the weeks ahead.
Flanked by House Speaker John Boehner and leading Ohio Republicans, Romney vowed to cut the deficit and work toward balancing the budget, open new markets for American products, and crack down on unfair trade practices by competitors, issues closely watched by voters dependent on Ohio's manufacturing base.
Obama's run-up to the convention was taking him through the battleground states of Iowa, Colorado, Ohio, and Virginia, four states he carried in 2008 that also are at the top of Romney's wish list.
The Democratic Party's convention, which starts Tuesday, will focus more on where voters want their lives to be in the next four years. Obama inherited an economy grappling with a sweeping recession, and the sluggish pace of the recovery has become one of Obama's greatest impediments to reelection.
The coming days, capped by Obama's speech on Thursday night, will crystalize his reelection pitch: an economy built on ending tax cuts for the rich and putting more effort into education, energy, tax reform and debt reduction. He will call Romney a peddler of failed trickle-down ideas that will hurt the middle class and the needy.
Previewing the convention, Obama campaign spokeswoman Jen Psaki told reporters aboard Air Force One on Saturday that by the end of the Charlotte convention, "voters will understand what is at stake."
Romney was capping his convention week in Ohio and Florida, the two most prominent states that remain up for grabs. The former Massachusetts governor's team said the Tampa, Fla., convention helped him present a clear contrast with Obama and showcase him as a viable alternative to the president on handling the economy.
"What Americans have seen over the last few days is a party and a Republican ticket absolutely committed to addressing the job crisis," said Romney adviser Eric Fehrnstrom. "You won't hear it from the Democrats in Charlotte next week."
Television ratings for the final night of the Republican convention were down compared with four years ago.
The Nielsen Co. said an estimated 30.3 million viewers watched Thursday night's coverage over 11 networks compared with more than 40 million over seven networks when John McCain delivered his acceptance speech in 2008.