The Shattered empire expansion introduces an ability, that Political cards may be used in a similar way as trade goods tokens.

As I understand it, I may use it (a Political card) as a substitution for one resource or one influence.

But what I do not know is whether I may use a Political card as a form of a bribe to another player (like with trade goods) or not?

Thanks for feedback.

I would argue no, just based on the fact that the politics cards is MORE than just a trade good even if that's all the player would use it for. You could bribe him by saying you would use that political card later, or even during the current assembly before he/she chooses who is speaker/who plays their politics cards (which has its own set of pitfalls, as the rest of the table hearing your arrangement could play cards or use their influence to block your bribe).

Definitely not.

You may spend a PC as if you were spending a TG. Other than that, they are not the same as a TG (and so are not a tradeable commodity).