WESTMINSTER, Colorado - US President Barack Obama takes his campaign to the Rocky Mountain state of Colorado Sunday as he and Republican challenger Mitt Romney fight for votes in key battleground states that will determine the outcome of the November election.

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. On Monday, he will travel to Louisiana to tour damage in the wake of Hurricane Isaac, which forced the Republican convention to start a day late. He will visit Virginia on Tuesday.

Gearing up for next week’s Democratic National Convention in Charlotte, North Carolina, Obama on Saturday 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 He mocked this week’s Republican gathering in Tampa, Florida for promoting an outdated policy agenda from the “last century” heavy on conservative social policies.

“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.”

Speaking in Sioux City at a later rally, the president criticized Romney for having “nothing to say” about Afghanistan, where US troops have been fighting the Taliban and their Al-Qaeda allies for nearly 11 years.

In the meantime, campaigning 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 have stopped looking for work or are 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.

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 ready 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.

However, the first tracking polls made during or after the Republican National Convention indicated the Republican nominee was not getting much of a so-called post-convention “bounce.”  In a Gallup survey out Saturday, Obama was still leading 47 percent to 46 percent. The same picture was in the Ipsos poll where the president was ahead by one percentage point, 44-43. Only a Rasmussen poll had Romney up - but only by three points - 47 percent to 44 percent.

The coveted “bounce” - a jump in the surveys - is usually due to extensive publicity received by a candidate during the convention prime-time events. But it largely depends on the candidate whether it evaporates a few weeks after or he manages to keep at least some of the benefit.

The focus of the political action has already 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 convention speech - which he said was packed with personal anecdotes and patriotic platitudes - lacked.