President Barack Obama and his Republican challenger Mitt Romney derided each other's record on job creation Saturday as they made a fresh push through key battleground states.

Gearing up for next week's Democratic National Convention in Charlotte, North Carolina, Obama rallied supporters in Iowa, a Midwestern state that helped launch his successful 2008 White House campaign.

He mocked this week's Republican gathering in Tampa, Florida for promoting an outdated policy agenda heavy on conservative social policies, and for "a lot of talk about hard truths and bold choices" that was light on the details.

"It was a rerun. We've seen it before. You might as well have watched it on a black and white TV," Obama joked to supporters in Urbandale.

"Let me recap it for you: Everything's bad, it's Obama's fault and governor Romney is the only one who knows the secret to creating jobs and (making) the economy" grow.

He lambasted Romney, the former governor of Massachusetts, for failing to offer any new ideas in his address to Republican activists.

Instead, Romney reiterated "the same old policies that have been sticking it to the middle class for years," Obama said. "They talked a lot about me. They talked a lot about him, but they didn't say much about you."

The president was on a four-day trip through swing states in the lead-up to his re-nomination at the Democrats' meeting in North Carolina.

In the crucial battleground state of Ohio, Romney said Obama had failed to fulfill his promise to revamp the sagging US economy, comparing his record to that of a failing sports coach.

He noted that 23 million people are now out of work or underemployed in the United States.

"Let me tell you, if you have a coach that's 0 to 23 million, you say it's time to get a new coach," Romney said in Cincinnati, fresh from being crowned the Republican Party's official presidential candidate. It's time for America to see a winning season again, and we're going to bring it to them."

Responding to Obama's earlier jab, Romney spokesman Ryan Williams said the president's policies "have taken us on a road to declining incomes, higher unemployment and more uncertainty for the middle class. And in the face of a record of failure, he offered no new solutions, just misleading attacks."

Stubbornly high US unemployment, which has topped eight percent for 43 consecutive months, and a bumpy economic recovery are widely seen as the biggest hurdles to Obama's hopes of winning the national vote on November 6.

A Rasmussen Reports poll showed Romney gaining a slight bounce from his party's convention, with 47 percent of support from voters nationwide against 44 percent for Obama.

The Republican contender had trailed the president by two percentage points when the convention began.

On the heels of the Republican nod, Romney and his White House running mate Paul Ryan are seeking to maintain momentum as Obama and his Democratic Party gear up for their convention starting Monday.

The pair were due to appear for a joint rally later in Jacksonville, Florida.

Ohio, along with Florida and Pennsylvania, is considered crucial to the outcome of the election.

Recent polls have shown Obama leading in Ohio, a major coal producer. But Romney is not far behind and is fighting hard - he has visited the state and outlined his goal to help make America more energy independent by developing natural resources.

"Paul Ryan and I have a plan that's going to get America working again. It's going to create about 12 million new jobs in America and about 460,000 jobs right here in Ohio," Romney said, touting his energy policy.

While Romney is hoping for a ratings bounce after the Republican convention, the focus of the political action has now shifted to the White House incumbent.

Obama's top adviser David Axelrod said Friday that the president would use the Democratic convention to deliver the specifics Romney's speech Thursday - which he said was packed with personal anecdotes and patriotic platitudes - lacked.

[Image via user DonkeyHotey via Flickr, Creative Commons licensed]