Roughly 10 percent of the delegates needed for the Democratic nomination are in play between Saturday and Tuesday, starting with caucuses in Michigan and Washington. Sen. John Kerry hopes to build on his lead. Sen. John Edwards and retired Gen. Wesley Clark are vying to become Kerry's chief rival. Former Vermont governor Howard Dean is pinning his fading hopes on the Feb. 17 Wisconsin primary. Hear NPR's Scott Simon and NPR's Scott Horsley.