Ah, sim. Eu entendo. Obrigada!"Eu não consigo dizer isso".
Posso (poder) implies authorization to some degree. If you say "Não posso abrir a porta", it doesn't mean that you can't because of physical inability, but rather because of some instruction preventing you.
Consigo (conseguir) implies actual ability. "Não consigo abrir a porta" means you can't physically open it.
Makes sense?
On-topic: This does not bode well for the US/UK.