And when he said “that involve Secretarwy Clinton”, he preceded it with “those type of investigations”. That referred back to whatever was done during the campaign.
So, the “it” is the campaign, the the campaign is the controlling factor.
The phrase, "matters related in any way to the campaigns for President of the United States", as seen in the letter, is not a less inclusive phrase than the phrase at the hearing, "investigations that involve Secretary Clinton and that were raised during the campaign or to be otherwise connected to it".
It's, "matters related in any way"!