How many votes would he take from Obama?

I have written often here that I fear Ron Paul running as an independent for the 2012 nomination, because he would take away votes from the Republican nominee. But, what about those votes he would take away from Obama Would those young people who voted for Obama in 1008 now go to Paul because of his desire to legalize drugs? This article raises some questions: http://spectator.org/archives/2012/01/18/election-deceptions