YOUNGSTOWN, Ohio—President Barack Obama this week will try to launch a political comeback amid the lowest approval ratings of his presidency and a growing sense of economic foreboding here and across the country among voters who are increasingly questioning their president's skills and priorities.

A new Wall Street Journal/NBC News poll of 1,000 adults, taken Aug. 27-31, found that 44% of Americans approve of the job Mr. Obama is doing as president, with more than half, or 51%, disapproving for the first time since his inauguration....