The 2008 presidential campaign has witnessed the rise of a whole arsenal of new political weapons, including Internet fundraising and sophisticated microtargeting of voters. For Sen. Barack Obama, however, the most powerful weapon has been one of the oldest.

Not since the days of the whistle-stop tour and the radio addresses that Franklin D. Roosevelt used to hone his message while governor of New York has a presidential candidate been propelled so much by the force of words, according to historians and experts on rhetoric.

Obama's emergence as the front-runner in the race for the Democratic nomination has become nearly as much a story of his speeches as of the candidate himself. He arrived on the national scene with his address to the 2004 Democratic National Convention, his campaign's key turning points have nearly all involved speeches, and his supporters are eager for his election-night remarks nearly as much as for the vote totals.