By Jon Frandsen, Senior Editor October 1, 2008 Ever since Barack Obama finally dispatched Hillary Clinton, analysts and pundits have been asking this question -- in an election year that has Democratic victory written all over it, how come Obama isn't trouncing John McCain in the polls? Even when Obama scores a margin of 5% or higher, as he has been this week, it's difficult for him to crack the 50% barrier in most national polls.Is it his mixed race? Is it because pollsters don't call cell phones? Is he being undermined by scurrilous e-mails tying him to extremist Muslims? Here's my question, looking at the respected Gallup tracking poll: Does it matter?Gallup's tracking poll shows what most other polls do -- any bounce McCain had from the selection of Sarah Palin and the GOP nomination has vanished and Obama is holding a narrow but steady lead. Yet even when Obama had his most commanding lead -- eight points -- he was unable to move beyond 50%. Many observers are beginning to speculate that 50% may simply be Obama's ceiling of support. But if so -- and as troubling as that might be to the Obama campaign and its supporters -- Gallup points out that cracking the 50% barrier simply may not matter much. "Gallup's historical trial heat trends show that the winners in 1988, 2000 -- both years with minimal third party candidate support suppressing the vote for the major party candidates -- rarely attained 50% or greater support from registered voters prior to Gallup's final pre-election poll. Voter support for George W. Bush only once exceeded 50% in his 2004 campaign against John Kerry, that being 53% in mid-September. In 1988, George H.W. Bush reached or surpassed the 50% mark once at the very beginning and then not again until the last two weeks of the campaign," Gallup says..