LONDON (AP) — In a real-life political drama mixing Shakespearean tragedy with “House of Cards,” Britain’s victorious anti-EU campaigner Boris Johnson saw his chances of leading his country evaporate Thursday after the defection of a key ally.

The former London mayor dropped his campaign to become Conservative Party leader and prime minister after Justice Secretary Michael Gove abruptly withdrew his support for Johnson and announced he would run himself.

Johnson, a prominent campaigner for Britain’s withdrawal from the 28- nation European Union, told a news conference where he was expected to announce his candidacy that the next Conservative leader would need to unite the party and ensure Britain’s standing in the world.

“Having consulted colleagues and in view of the circumstances in Parliament, I have concluded that person cannot be me,” he said to the astonishment of gathered journalists and supporters.

Johnson paraphrased Shakespeare’s “Julius Caesar,” saying it was “a time not to fight against the tide of history but to take that tide at the flood and sail on to fortune.” It appeared to be a dig at Gove – the reference is to a line spoken by Brutus, the Roman leader’s ally turned assassin.