WASHINGTON, Sept. 13 — A day after President Bush's speech to the United Nations, many Democrats are still tormented and uncertain over Iraq, not ready to give President Bush a blank check to wage war, yet wary about opposing him.The party's dilemma comes after a year in which Democrats tried to hug Mr. Bush closely on the war on terrorism but turn the political debate to domestic issues. Iraq has changed the equation. As the issue moves to center stage in Congress, many Democrats are showing clear misgivings about Mr. Bush's policy. But their positions are complicated by the fears...