Are my donors' contributions tax deductible during a fundraiser?

We did some research and found this from the IRS: http://www.irs.gov/pub/irs-pdf/p526.pdf. 

It explains what is and isn’t tax deductible for charitable giving. 

Check out Page 6 and the section called “Contributions You Cannot Deduct”. This should answer all of your questions.

(Except for the chicken and the egg debate. You're on your own with that one.)