I am certain there are people inside the Democrat Party and the liberal media who want to scuttle this, because they know it is going to end up exiling them from power for a couple of generations. Hence I think the leaker was a loyal Democrat.
Or possibly one of Hillary’s disciples, it they can bring down this bill it will significantly damage his presidency leaving her to step in as a strong primary challenger. Hillary’s people think she was cheated and want a do over.