Former British Prime Minister David Cameron took a swipe at Boris Johnson, accusing the current prime minister of only joining the leave campaign during Brexit talks in order to “help his political career.”

In excerpts from his memoir For the Record published over the weekend, Cameron charges the leaders of the “Leave” campaign with declaring “open warfare” on him and claims they were guilty of “lying” to the public to win the referendum. He also accuses Johnson of backing Brexit not in the name of sovereignty, but because he wanted to “become the darling of the party.”