(CNN) - TV commentator and Tea Party favorite Christine O'Donnell defeated U.S. Rep. Mike Castle in Delaware's Republican U.S. Senate primary Tuesday.
With 99 percent of precincts reporting, O'Donnell led Castle 53.2 percent to 46.8 percent, according to The Associated Press.
O'Donnell on Tuesday night thanked her supporters, including Tea Party groups, saying they "rallied everyday Americans outside of the political establishment, [got] them involved and created a grassroots network that made all of this possible."
"Don't ever underestimate the power of we, the people," O'Donnell said to raucous cheers from her supporters. "We, the people, will have our voice heard in Washington, D.C., once again."
Updated 11:13 p.m.