In the space of an hour this weekend, Sens. Hillary Rodham Clinton (N.Y.) and Barack Obama (Ill.), using some of their most pointed and forceful rhetoric of the campaign, framed in stark terms the choice for Democrats deciding their party's presidential nomination.Clinton gave a strong speech at the Iowa Democratic Party's annual Jefferson-Jackson Dinner late Saturday night, but Obama, criticized for occasional lackluster performances on the campaign trail, delivered one of his most focused and powerful addresses. In the view of many in the audience, he emerged as the oratorical winner at the biggest Democratic political event in Iowa before the state's January caucuses.Most of those in the audience Saturday night already knew whom they would back in January, but not all. Barbara and Mike Donnelly arrived not certain whom they would support in the Democratic caucuses.The Oskaloosa couple left with colorful glow necklaces, handed out by Obama's campaign, peeking out from under their coats."We just think he's a very strong character," Barbara Donnelly said. Obama's speech "crystallized it for me," Mike Donnelly said. "I like Hillary and Edwards. But there was something about Barack tonight. He was so forceful."