CHARLOTTE, N.C. — His re-election in doubt, President Barack Obama acknowledged slow progress toward solving the nation’s economic woes Thursday night but declared in a Democratic National Convention speech, “Our problems can be solved, our challenges can be met.”

“The path we offer may be harder, but it leads to a better place,” he said in excerpts of his prime-time speech released in advance.

His speech was the final act of his national convention, and the opening salvo of a two-month drive toward Election Day in his race against Republican rival Mitt Romney. The contest is close for the White House in a dreary season of economic struggle for millions.

With unemployment at 8.3 percent, Obama said the task of recovering from the economic disaster of 2008 is exceeded in American history only by the challenge Franklin Delano Roosevelt faced when he took office in the Great Depression in 1933.

“It will require common effort, shared responsibility and the kind of bold persistent experimentation” that FDR employed, Obama said.

In an appeal to independent voters who might be considering a vote for Romney, he added that those who carry on Roosevelt’s legacy “should remember that not every problem can be remedied with another government program or dictate from Washington.”

The convention’s final night also included a nomination acceptance speech from Vice President Joe Biden, whose appeal to blue collar voters rivals or even exceeds Obama’s own.

Delegates who packed into their convention hall were serenaded by singer James Taylor and rocked by R&B blues artist Mary J. Blige as they awaited Obama’s speech.

Actress Eva Longoria was on the program, as well. “No empty chairs,” she said, a reference to actor Clint Eastwood’s mocking reference to Obama at Romney’s Republican National Convention last week in Florida.

As part of the excerpts released in advance, Obama’s campaign said he would set a goal of creating one million new manufacturing jobs by the end of 2016 and push for more aggressive steps to reduce American dependence on foreign oil.

Still, he said, “The truth is it will take more than a few years for us to solve challenges that have built up over a decade.”