In one, Mr. Schweizer had obtained a cache of emails from Bevan Cooney, the former Hunter Biden associate who is in prison for fraud.
Using those emails, Mr. Schweizer and a researcher for his watchdog group, the Government Accountability Institute, have published several stories, including one trying to draw a link between Hunter Biden’s dealings in China and his associates’ efforts to arrange meetings in Washington for Chinese business leaders during the Obama administration.
Mr. Schweizer’s institute, of which Mr. Bannon was a co-founder, has received funding from Ms. Mercer’s family, according to tax records. The Mercers have also provided funding to Breitbart News, which was previously run by Mr. Bannon and which has been publishing Mr. Schweizer’s articles.
Separately, Mr. Schweizer was consulted in September about the claims made by Mr. Bobulinski, who had worked in 2017 with Hunter and James Biden on a joint venture with a Chinese conglomerate that fizzled.
According to two people familiar with the events, Mr. Bobulinski, an investor who had done business related to China, had approached allies of Mr. Trump, seeking assistance to publicize his claims.
Mr. Bobulinski, who was admittedly bitter about the way the proposed deal unraveled, was referred to Mr. Passantino, who previously worked in the White House Counsel’s Office and works with a campaign-affiliated group, Lawyers for Trump.
In an effort to vet Mr. Bobulinski’s claims and documents, Mr. Passantino was referred by Mr. Gingrich, a longtime client, to Mr. Schweizer, who wrote a book in 2018 about business dealings involving Hunter Biden in Ukraine, China and elsewhere.