Gallup’s daily tracking poll is showing a bounce for Sen. Barack Obama (D-Ill.), who now holds a 48 percent to 42 percent lead over Sen. John McCain (R-Ariz.), after falling behind 46 percent to 44 percent as of two days ago.

The lead could grow, as the Gallup Poll uses a three-day rolling average, and only one of the three days’ polling, occurred after Sen. Hillary Clinton’s (D-N.Y.) speech Tuesday night.

Obama had a statistically insignificant 45 percent to 44 percent lead in Wednesday’s tracking poll, so this latest poll showed a marked shift in his favor. The margin of error is 2 points.

Gallup said the formal convention bounce won’t be tabulated until Monday’s tracking poll, which will use data from Friday, Saturday and Sunday night polling. Gallup also said factors that could affect the convention bounce are McCain’s imminent selection of his running mate and news coverage of Hurricane Gustav as it appears likely to enter the Gulf of Mexico.