CHARLOTTE, N.C. — President Barack Obama lampooned the just-completed Republican National Convention as better-suited to an era of black-and-white TV and " trickle-down, you're on your own" economics Saturday, and declared that Mitt Romney "did not offer a single new idea" to fix the economy.

"There was a lot of talk about hard truths and bold choices, but no one actually told you what they were," Obama said in Iowa, chuckling, as he set out on a three-day tour of battleground states in the run-up to his own convention. Later, Obama said, the Republican gathering was so rooted in the past, there should have been a rabbit-ears antenna on the convention hall.

Yet even the site of Obama's convention, Charlotte, N.C., served as an unwelcome reminder to the Democrats of an economy so weak that it threatens his chances for re-election.

The president carried North Carolina in 2008, but the state's unemployment rate is pegged at 9.6 percent, well higher than the nation's 8.3 percent and tied with next-door South Carolina for fifth from the bottom.

Obama's convention opens Tuesday at the Time Warner Cable arena 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 also will speak. Vice President Joe Biden delivers his own 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 will hear the speech at the site, which has a capacity of nearly 74,000 for football.

Democrats are taking their turn in the convention spotlight just days after the Republicans met in Tampa, Fla., to nominate former Massachusetts Gov. 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 recession recovery of the post-World War II era.

The economy has been the top-rated issue in opinion polls all year, and the president is eager to turn the focus onto Romney on that subject.

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.

"Gov. 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.

The Republican challenger "said ending the war in Iraq was tragic. I said we'd end that war and we did," Obama said.

Romney said late last year, in a veterans roundtable, "The precipitous withdrawal is unfortunate. It's more than unfortunate, I think it's tragic. It puts at risk many of the victories that were hard won by the men and women who served there."

Obama, pointing to successes, declared, "I said we'd take out bin Laden and we did."

His audience cheered the mention of the demise of the architect of the Sept. 11, 2001, terrorist attacks, who was killed in his hideout in Pakistan by U.S. Navy SEALs last year. Obama ordered the raid, and even Republicans credit him for the decision.

Romney campaigned in Ohio during the day – the opening of the college football season – and proclaimed it was time the country had a winning season after years of a sluggish economy and high unemployment.

Referring to the number of jobless in the country, Romney told his own cheering crowd, "If you have a coach that's zero and 23 million, you say it's time to get a new coach."

He also pledged to cut the federal deficit and "get us on track for a balanced budget."

Yet Romney has yet to produce a budget for public inspection. Nor did he mention that, as chairman of the House Budget Committee, Ryan wrote a plan projecting the deficit would decline each year from 2013 through 2017 but then begin an inexorable rise again. Additionally, the federal debt is projected to rise each year, from a current level of nearly $16 trillion to an estimated $25 trillion at the end of 2022.

Obama made Iowa his first stop on what his campaign billed as "The Road to Charlotte."

Obama spoke in Urbandale, outside Des Moines, on a sprawling 500-acre property. With barns, American flags and Obama banners all around, the late summer scene offered him the quintessential heartland backdrop. He later spoke at a rally in Sioux City.

He told the crowd Iowa was first on his schedule "because it was you, Iowa, who kept us going when the pundits were writing us off."

There was another reason, as well.

Polls make the state one of eight or so battlegrounds where the election is most likely to be decided. The president carried Iowa in 2008, and in an indication of the struggle he now faces, he has been lavishing time on it in recent weeks. He spent three days in August on a bus tour that traversed the state from west to east.

Following two stops in Iowa, Obama was flying to Colorado for a Sunday appearance before college students at the University of Colorado.

Obama's schedule for Monday includes an appearance in Toledo, Ohio, yet another battleground state, before a trip to Louisiana to inspect damage from Hurricane Isaac.

Romney visited Louisiana on Friday.

Television ratings for the final night of the Republican convention were lower than four years ago. The Nielsen Co. said an estimated 30.3 million viewers watched Thursday night's coverage of Romney's acceptance speech. That was down by one-fourth from 2008, when John McCain spoke on the final night of the Republican gathering in St. Paul., Minn.

___

Feller reported from Urbandale and Sioux City, Iowa. Associated Press writers Kasie Hunt in Cincinnati, Beth Fouhy in Charlotte and Steve Peoples in Columbus, Ohio, contributed to this report.

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