A former British prime minister from Boris Johnson’s own Conservative party is urging the public to vote against Conservative candidates in the country’s general election next week. In an unprecedented intervention, Sir John Major is expected join an election rally aimed at preventing Johnson from winning enough seats for a parliamentary majority when voters go to the polls next Thursday. He’s expected to be joined by his successor as prime minister, Tony Blair, at the event in London on Friday. The pair will urge people to vote tactically for the pro-EU candidates most likely to defeat the Conservatives in their local seats. Both Blair and Major support a second referendum on Brexit. In a pre-recorded speech ahead of the rally, Major will say old “tribal loyalties” of British politics have been loosened by Brexit, and that next week’s vote is the “final chance” to stop it.