(Bloomberg) -- Boris Johnson made his name with his turn of phrase. Before he entered Parliament he was a journalist better known for his wit than for his accuracy, and as a politician, he has often been able to force his way up the agenda by saying something entertaining -- or offensive.

That might explain his reluctance to apologize at his campaign launch Wednesday, when challenged over his 2018 claim that Muslim women who cover their faces looked ridiculous, resembling bank robbers and letter boxes.

Johnson eventually said he was “sorry for the offense I’ve caused,” but his preamble was a long defense of his right to offend.

“It’s vital for us as politicians to remember that one of the reasons that the public feels alienated now from us all as a breed, is because too often they feel that we are muffling and veiling our language, not speaking as we find. What they want to hear is what we genuinely think.”

He brushed off one reporter’s suggestion that people who have worked closely with him don’t think he is fit to lead because of the gaffes and inflammatory language he has used in the past. "Of course occasionally some plaster comes off the ceiling as a result of some phrase that I have used.”

Saying what he likes has brought Johnson to the threshold of becoming prime minister. But as the favorite, he now has it all to lose. An offhand comment could blow up on him, and Johnson’s past remarks about Africans’ “watermelon smiles” or men finding that their wives will “have bigger breasts” if they vote Conservative, suggest his desire to shock is far stronger than any sense of caution.

The key test for Johnson in the coming days is self-control. And to help him pass it, his team are keeping him away from the cameras.

To contact the reporter on this story: Robert Hutton in London at rhutton1@bloomberg.net

To contact the editors responsible for this story: Tim Ross at tross54@bloomberg.net, Emma Ross-Thomas

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