hot potato
US /hɑt pəˈteɪ.toʊ/
UK /hɑt pəˈteɪ.toʊ/

1.
a controversial issue or problem that is awkward or unpleasant to deal with
:
•
The issue of climate change has become a real hot potato in political debates.
•
No one wants to deal with that hot potato of a budget deficit.