Pai abruptly withdrew from the conference on Wednesday.
The sources added that federal law enforcement agencies have "intervened in the matter".
This isn't the first time FCC officials have received threats related to the move.
While it's likely that the majority of attendees at CES do not have a favorable opinion of Pai, the reason for the cancellation is unclear since the FCC declined to comment.
Pai has consistently attended CES for half a decade.
Why it's so hard for United States to crack down on Pakistan
The country received more than $1 billion in US assistance in 2016. Zubair Iqbal, an economist focusing on Pakistan , told Newsweek .
It's clear that the FCC's 2015 "net neutrality" order, which the pro-regulatory advocates now insist is gospel, actually allowed ISPs to engage in the very practices that they loudly proclaim the Commission has just now authorized.
Speaking about the repeal order, FCC Commissioner Jessica Rosenworcel who voted against the bill, said: "Going forward, our broadband providers will have the power to block websites, throttle services, and censor online content". Neither he, the FCC, nor the Consumer Technology Association, which organizes the trade show, offered an explanation for his withdrawal.
Only by ignoring these two inconvenient truths are pro-regulatory advocates able to falsely claim that the FCC has left consumers in danger of being denied any remedy for abusive or anti-competitive practices by internet service providers.
"Pai has attended CES in Las Vegas for the last five years, and this would have been his first appearance as chairman of the FCC", Business Insider notes. But Pai and his family have faced harassment over the controversial decision to repeal the rule.
Pai has come under heavy criticism by net neutrality supporters after the agency voted in December to dismantle rules passed by the Obama administration. When no bomb was found the meeting continued, and the commissioners went ahead with their planned vote on the repeal.