Updated

Defiantly protecting his record, President Obama on Tuesday challenged Republicans to explain why they oppose the spending boosts and tax credits that he says have helped communities rebound. Said Obama: "Tell us why doing nothing would be better for America."

In the latest campaign stop for his economic efforts, this one in struggling Ohio, Obama took concerted swipes at what he called the "unified, determined opposition of one party." He said it is not too late for bipartisanship and appealed for it -- but not until after criticizing those he said were badmouthing his steps.

"If the just-say-no crowd had won out -- if we had done things the way they wanted to go -- we'd be in a deeper world of hurt," Obama said in the swing state of Ohio, where the unemployment rate is close to 11 percent, above the already-high nationwide average of near 10 percent.

The president came to explain and defend the economic stimulus spending, tax credits, extended unemployment benefits and other help that he championed with support from mostly the Democrats in Congress. Without it, he said, "the steady progress we are beginning to see across America just wouldn't exist."

Republicans have opposed the steep cost of Obama's plans and criticized the pace of the promised recovery, particularly on the key measure of jobs.

His comments came on a day of closely watched primary elections in Kentucky, Pennsylvania and Arkansas. Two Democratic senators -- Arlen Specter of Pennsylvania and Blanche Lincoln of Arkansas -- face stiff challenges from fellow Democrats who say the senators were not sufficiently loyal to party priorities.

The president, meanwhile, is on a drive to show people that the country's economy is getting better even as their individual situations may not be yet. He got out of Washington and donned a hardhat, goggles and a fire-retardant jacket while touring a hot, noisy plant where metal piping was being manufactured.

And he acknowledged that some may not be impressed by a president swooping into town when all they want is to see the headline saying: "You're hired."

Still, he tried to keep spirits up to employees at V&M STAR, a place he said is benefiting directly from his economic policies.

The parent company of the V&M is spending $650 million to build a 1 million-square-foot mill in Youngstown now that the nearby Norfolk Southern railroad is building a spur, thanks to money from last year's stimulus act. To applause from the assembled workers, Obama said it would be the biggest industrial plant built in the region since a GM plant went up in nearby Lordstown in the 1960s.

Overall, the U.S. economy grew at an annual rate of 3.2 percent in the first three months of this year. In April, payroll jobs grew by 290,000, the most in four years. The unemployment rate rose to 9.9 percent as more people began or resumed job searches -- a sign that more are feeling more optimistic about the job market.

Obama tried to put the burden on Republicans for their opposition. "For all the things we've gotten done despite the unified, determined opposition of one party, imagine how much farther we could have gotten if I'd gotten a little help," he said.

His stop was the latest on White House to Main Street tour of towns and businesses, often in economically depressed regions.

The president was in Buffalo, N.Y., last week, and before that made stops in Allentown, Pa., Charlotte, N.C., Savannah, Ga., and Quincy, Ill.

His message has been consistent: The economy is beginning to recover thanks in part to his administration's policies, many of them unpopular with voters.

It's not clear that Obama's tour is doing much to turn around public sentiment. An Associated Press-GfK poll released Saturday found that just 35 percent of respondents said the country is heading in the right direction, the lowest measured by the AP-GfK survey since a week before Obama took office in January 2009. His approval rating remains at 49 percent, as low as it's been since he become president.

Tuesday may bring a referendum on incumbent Democrats -- and to a degree the president -- with Obama-backed Democratic senators in Pennsylvania and Arkansas facing strong challengers from the left. In a special House race in southwestern Pennsylvania that's attracting high spending from the national political parties, a Republican and Democrat are facing off to see who will serve out the final few months in the term of the late Democratic Rep. John Murtha.