Gallup Poll: McCain Catches Obama @ 45%
Item: Obama, McCain tied at 45% apiece as Democratic Convention begins/Gallup Poll
More Info: The last Gallup Poll Daily tracking polling conducted before the beginning of the Democratic National Convention shows Barack Obama and John McCain tied at 45%. The latest update includes two days of interviewing following Obama's selection of Sen. Joe Biden as his vice presidential running mate, and neither day showed an improved performance for Obama.
Question: Why has Repub John McCain caught Demo Barack Obama in the polls, after Obama rode a wave of excitement to the Democratic nomination and appeared unbeatable?