One of the top aides to presidential candidate Hillary Clinton quit on Thursday after being involved in suggesting that it would be hard for Barack Obama to topple the Repulicans should he receive the party's nomination due to his drug use in his teens. The aide, Bill Shaheen, also talked about the potential of future allegations about Obama dealing drugs during that period, something Obama insists is not true.

Commentary: Clinton apologized to Obama over the flap. Obama acknowledeged his past drug use in his first book, "Dreams of my Father" and notes that youthful period of transgressions as being an important part of helping him turn his life around. The Obama campaign seemed reluctant to accept theClinton apology as it appeared that the questions continued a recent line of attack from the advisory team of the presidential frontrunner.