To counter mis/disinformation, fact-checking organisations are used as sources by journalists to challenge false or misleading statements, especially during election campaigns. But how different fact-checkers editorially construct their analysis and question dubious claims remains under-researched. Drawing on a case study of reporting during the UK’s 2019 General Election campaign, we interviewed senior editors and journalists, and conducted a systematic content analysis of 238 fact-checking stories produced by BBC’s Reality and Channel 4’s Full Fact, along with a fact-checking organisation, Full Fact, in order to critically assess their editorial judgements about the selection of news and use of sources. Our study revealed that fact-checking services at the BBC and Channel 4 were not closely integrated into their routine news production, and that the independent fact-checker, Full Fact, questioned claims differently to broadcasters. We also found that the broadcast agenda of fact-checkers centred on party political agendas and drew on a narrow range of institutional sources to question claims. Overall, we argue that if broadcasters relied more heavily on their fact-checking in routine coverage—beyond election campaigns—they would more effectively counter mis/disinformation, especially if a wider range of expert sources were drawn upon to scrutinize claims.