Of ?!!

[Manhattan]

Hi there

"Obama's hometown of Chicago confident in his chances"

I understand it's definition at least I think I've understood!! But not entirely and clearly! Can someone enlighten me about role of "Of" in the sentence above? what is the structure?!
What would it become if "Of" were not there?!
ie:
"Obama's hometown, Chicago confident in his chances"

Thanks and sorry if my question is so amateur!

[Marius Hancu]

"Obama's hometown, Chicago, [comma] confident in his chances"

This would be good only for a title or a caption. Too short for any meaningful sentence.

Obama's Hometown and Chicago are practically appositives here. Of is used in such situations.

It means:

"Obama's hometown, which is Chicago, is confident in his chances"

[OddThomas]

Often in headlines, the copula is omitted. A B = A is B
This mean that whatever expression is A is equivalent to whatever is B. Governor to sign bill = Governor is to sign bill
Suspect held in jewelry heist = Suspect is held in jewelry heist
Obama's hometown of Chicago confident in his chances = Obama's hometown of Chicago is confident in his chances
One of the two dozen definitions of of is specified as. You can literally substitute this definition for of into the headline:Obama's hometown specified as Chicago is confident in his chances

[Manhattan]

Thank you very very much my dear friends!