`` Late Show With David Letterman . '' President Obama 's visit first time a sitting president has been ` ` Letterman '' guest . President says he will ask ` ` tough questions '' before sending more troops to Afghanistan . President says he does n't think racism causes opposition to health care overhaul . What did both Malia and Sasha do this summer ? They ` ` time off , '' he says .
President Obama 's visit first time a sitting president has been ` ` Letterman '' guest . President says he will ask ` ` tough questions '' before sending more troops to Afghanistan . President says he does n't think racism causes opposition to health care overhaul . What did both Malia and Sasha do this summer ? They ` ` time off , '' he says .