What political significance do widely-shared sources on social media carry? Efforts at documenting media content have produced useful insights about political phenomena—including right-wing populist movements that have recently been theorized as comprising defensive publics which seek to preserve centers of social, economic, and cultural power. Yet we argue patterns of sources’ visibility—not just content—also serve defensive purposes. Specifically, we conceive acts of sharing as rhetorical resources that highly-visible members of defensive publics use to mediate relationships within and across political groups. Our evidence comes from mixed-methods anaysis of 1.16 million French-language immigration-related posts on Twitter/X made between May 2020-September 2021, computationally-derived ideological embeddings of 44,810 of these users, baseline measures of the prevalence and types of hyperlinks shared by broadly politically interested French-language users beyond immigration, and 13 interviews with high-profile hard right-affiliated posters in our dataset including senior French politicians. Right- and extreme-right users are more likely than centrist or left users to engage in reposting external sources, and at significantly higher rates. Moreover, these users tend to repost both hyper-partisan sources at the extreme right as well as ones across the ideological spectrum. Sharing hyper-partisan and alternative sources redresses perceived censorship by mainstream media, while sharing mainstream sources validates some users’ views. This latter objective is enhanced by reposting sources that convey statistical evidence to signal credibility and respectability. Our results contribute novel and—in the case of the interviews—rare evidence about which sources are more visible on a globally consequential issue and the likely reasons for their persistence.