CHARLOTTE, N.C. – His re-election in doubt, President Barack Obama conceded only halting progress Thursday night toward fixing the nation’s stubborn economic woes, but vowed in a Democratic National Convention finale, “Our problems can be solved, our challenges can be met.”

“Yes, our path is harder – but it leads to a better place,” he declared in a prime-time speech to convention delegates and the nation that blended resolve about the challenges ahead with stinging criticism of Republican rival Mitt Romney’s proposals to repair the economy.

He acknowledged “my own failings” as he asked for a second term, four years after taking office as the nation’s first black president.