https://www.theverge.com/2018/5/25/17394670/facebook-ad-rules-verification-problems-rose-boyanton

Facebook introduced new disclosure rules for political advertisements this week designed to block bad actors from meddling in elections. But in the meantime, the rules are blocking legitimate candidates from buying Facebook ads — and at least one congressional candidate in Mississippi says it could tip the election toward his opponent.

The rules that Facebook implemented in the United States this week require anyone wishing to buy a political ad to verify their identity. To do so, Facebook mails a card to their physical location containing an authorization code. Only after the candidate or advocacy group enters that authorization code on Facebook can they purchase political ads.