PETERSBURG, Va. — President Obama spoke encouragingly Friday about the improving economy, including the tentative revival of the manufacturing sector, as he touted his record on a factory floor in this battleground for his re-election campaign. Speaking to workers at an aircraft-parts manufacturing plant, Obama outlined progress made on his watch in the auto industry and other parts of the economy, holding up a February jobs report that White House officials called encouraging as evidence. But he also hammered Congress, chiding lawmakers for moving slowly on what he said were important initiatives to improve the economy and educate the future...