Political observers have speculated that Obama's running mate will make his first campaign appearance at the Springfield rally.

The Obama camp said that stop would be the first in a trip that takes the Democratic nominee through "several" battleground states on his way to accepting the nomination in Denver next week. The campaign did not specify which states Obama would be visiting en route.

The Illinois Democrat first announced his candidacy at the same spot in February 2007. There has been media speculation that Obama will announce his vice presidential pick at the end of this week -- with dates ranging from Wednesday to Friday being mentioned.

 Sen. Josephe Biden (D-Del.) appears to be the current favorite for the No. 2 slot, although Indiana Sen. Evan Bayh and Virginia Gov. Tim Kaine are both said to be under consideration.

The Democratic National Convention begins in Denver on Monday, Aug. 25th.