The campaigns of Senator John McCain and Senator Barack Obama engaged in a sharp and testy exchange on education last week, making the topic the center of debate for the first time since the long race for the presidency began. Neither candidate changed course on the policies he is promising to pursue. However, Obama sought to distinguish himself from McCain in two public appearances, trying to portray himself as a bipartisan problem-solver for schools. Each campaign also released a hard-hitting TV ad attacking the other candidate's record on education. The attention to education in the first week of campaigning after the back-to-back Democratic and Republican conventions was heartening to some observers. However, it is unlikely that a substantive debate will emerge from the week's activities, one political scientist said, because the campaigns appear to be focusing on the opposing candidate's character and personality.