The phrase "leading campaigner" refers to a person who is at the forefront or in a prominent position of advocating for a particular cause or leading an organized effort to achieve a specific goal. Full definition
Wes Streeting wrote today: «She may be one of the country's leading campaigners for civil liberties, but we shouldn't pretend that everything about the timing and nature of this appointment doesn't stink.» (totalpolitics.com)
Only Gordon Brown can resolve Gurkha tensions between the Home Office and the Ministry of Defence (MoD), Labour's leading campaigner on the issue has said. (politics.co.uk)
And it tore into John Mann, a Labour MP and leading campaigner against anti-Semitism, for «haranguing and insulting» Ken Livingstone, who was suspended from Labour after saying Adolf Hitler supported Zionism. (dailymail.co.uk)