Former President Barack Obama knocked down one of former President Donald Trump’s most central pitches to voters for re-election at a Pittsburgh rally Thursday evening: that Trump was a masterful steward of the economy. In fact, Obama argued, Trump just took credit for what his predecessor accomplished. “Some think, I remember that economy when he first came in being pretty good,” said Obama. “Yeah, it was pretty good — because it was my economy. It wasn’t something he did. I spent eight years cleaning up the mess that the Republicans had left me.” Want more breaking political news? Click for …