David Axelrod, former senior adviser to President Obama, will begin as a CNN senior political commentator tomorrow, September 4; he will be unveiled on The Lead With Jake Tapper. It’s presumed this means Axelrod’s tenure as political analyst on MSNBC has come to an end. At CNN, he will add insights and analysis across CNN's domestic, digital, and international networks. CNN’s Washington bureau chief Sam Feist broke the news this morning: Thrilled to announce that @David…