<p>Two years after a surge of national unity in the wake of the terrorist attacks of Sept. 11, 2001, the United States is once again a 50-50 nation, shaped by partisan divisions as deep as ever that stand between President Bush and reelection.</p>
<p>A year before Election Day, growing questions about the U.S. mission in Iraq and continuing anxieties about the jobs picture, despite recent signs of economic improvement, dominate the political agenda, according to interviews with scores of voters in all regions of the country and amplified by a new Washington Post-ABC News Poll.</p>