GOP Primary Field Continues To Grow

Rick Klein, senior Washington editor for ABC "World News" and host of the “Top Line” webcast

Rick Santorum, the former Pennsylvania senator, threw his hat in the ring for the GOP primary race. Santorum, a favorite among his party's social conservatives, joins six other Republican candidates. Not in that list is Sarah Palin, who is defending her account of Paul Revere's role in history while on her bus tour of America.

We take a look at the weeks in politics, including how Pres. Obama's troop withdrawal strategy in Afghanistan could affect his reelection campaign.