lead up to something phrasal verb [not in passive] ( see also ↑ lead )
1 . if a series of events or a period of time leads up to an event, it comes before it or causes it:
the weeks that led up to her death
the events leading up to his dismissal
2 . to gradually introduce an embarrassing, upsetting, or surprising subject into a conversation:
She had already guessed what he was leading up to.