The new LA Times/Bloomberg poll

Overall, Obama holds a narrow edge over the Arizona senator, 45% to 43%, which falls within the poll’s margin of sampling error of plus or minus 3 percentage points. In June, Obama was ahead by 12 points. Other polls at that time showed him with a narrower lead.

More striking than the head-to-head matchup, however, is the drop in Obama’s favorable rating in the run-up to his selection of a running mate and the Democratic National Convention next week in Denver.

Obama’s favorable rating has sunk to 48% from 59% since the last Times/Bloomberg poll in June. At the same time, his negative rating has risen to 35% from 27%.

By comparison, McCain’s ratings have hardly budged during the same period: 46% of voters have a positive feeling about him; 38% give him negative ratings.

It seems that with the celebrity theme, the McCain campaign finally hit on something that is sticking.