enough . . . to

[nyota]

1. There are not enough experienced political figures left for the President to . . . .
2. He has quite enough athletic talent to . . . .
3. There's not enough of the green paint left for us to . . . .

Why do we use of in the third sentence and not in the first or second one?

[Raymott]

1. There are not enough experienced political figures left for the President to . . . .
2. He has quite enough athletic talent to . . . .
3. There's not enough of the green paint left for us to . . . .

Why do we use of in the third sentence and not in the first or second one?

You could say: 3. There's not enough green paint ... ", which would be cognate with your other sentences.
When you add "the", you have to use "of the".