With less than two weeks left until election day, President Barack Obama talks exclusively with NBC's Brian Williams about the tightening of the race between him and Republican presidential nominee Mitt Romney. In the first of a series of interviews during his two-day campaign blitz to seven states, the president said he has delivered on promises made during the 2008 campaign. Brian Williams' full, behind-the-scenes profile airs Thurs., Oct. 25 at 10 p.m./9 central on NBC's Rock Center with Brian Williams.