We Build the Wall was popularized in Instagram and Twitter posts boasting of ties to Mr. Trump. It was also promoted by Donald Trump Jr. and assembled an advisory board of right-wing luminaries. They included David Clarke, the former sheriff of Milwaukee County in Wisconsin; Kris Kobach, the former Kansas secretary of state; and Erik Prince, the founder of the private military company Blackwater, now known as Academi. We Build the Wall was created to spur on the Trump administration, which ultimately built about 450 miles of a wall along the border. Brian Kolfage had launched a GoFundMe campaign to further the effort. Prosecutors said that he raised about $17 million in a week with Timothy Shea’s help. But GoFundMe suspended the campaign, saying it would return the donated money unless Mr. Kolfage found a nonprofit group to administer it, prosecutors said. Soon Steve Bannon and Andrew Badolato, who were working on a nonprofit meant to promote economic nationalism and American sovereignty, joined the campaign. That led to the formation of We Build the Wall. Most donors who had given to the GoFundMe campaign transferred their money to the new group, and by the end of 2019 We Build the Wall had raised about $25 million.