Politicians won't debate fringe candidates because they don't want to give them credibility as an opponent. Terrorists are fringe opponents and do not represent the majority anywhere (not even during the U.S. Revolution when a majority of people wished to remain British subjects). Therefore by flaming fear, declaring "war", and debating the ideology in the public forum these same politicians legitimize the terrorists.
What they won't do for their fellow patriotic polical rivals they will do for foreign terrorists. So, in a way, when politicians say we should worry about the terrorists they then are sympathizing with the enemy.
See DRShow.org - Interview with Louise Richardson: "What Terrorists Want" (Random House)
