CBS News: President Obama's State of the Union speech Tuesday will be in part driven by events - chief among them the "shellacking" he took in the midterm elections and the assassination attempt on Democratic Rep. Gabrielle Giffords of Arizona. But it will also, inevitably, be driven by politics - and, along with the tax cut compromise worked out in December, set the groundwork for Mr. Obama's argument to voters that he deserves to be reelected in 2012.