In a surprise move, former London mayor and key “Leave” vote advocate Boris Johnson announced Thursday that he will not seek to become the next leader of the U.K.’s Conservative Party; because “Remain” advocate David Cameron is resigning, the next Conservative leader will become U.K. prime minister.

Here’s Johnson’s announcement:

Johnson had been considered the favorite to replace Cameron. In his absence, the leading candidates appear to be justice minister Michael Gove—a Johnson ally whose recent move to enter the race may have triggered Johnson’s change of heart—and home secretary Theresa May.

• Brexit
• United Kingdom