A national poll shows that Obama and McCain are virtually tied as they prepare to announce their running mates and attend their respective conventions in the next two weeks.

The poll, released on Tuesday, shows Obama leading McCain by a 45 - 43 percent margin which falls into the three percent margin of error.

The closing in of the race suggests that McCain’s ad campaigns designed against Obama did have an influence on the voters’ psyche. The overseas conflict between Russia and Georgia also may have played a role in highlighting McCain’s foreign policy credentials.

Obama’s favorable rating dropped 11 points during the period falling from 59 percent to 48 percent while McCain’s numbers remained constant.

“Personal criticism of your opponent is almost always going to cause a backlash unless you can find a way to link it to a policy matter,” said Dan Schnur, director of the Jesse M. Unruh Institute of Politics at the University of Southern California.  “And these celebrity ads, particularly the follow up ones, have done an outstanding job of linking criticisms personally to Obama’s policy credentials.”

Those questioned in the poll said that they would have more belief in John McCain during a foreign affairs crisis.  Seventy-seven percent feel McCain would “deal wisely” with the situation compared to 63 percent for Barack Obama. One-third of the participants have apprehensions about Obama’s patriotism while nine percent have questions about McCain’s.

However, Independents still favor Obama by a considerable margin of 47 percent to 36 percent.