NPR: Can UK's new Prime Minister pull off Brexit? Here's what to know

Sam Lowe, a senior research fellow at the Centre for European Reform, a London think tank, lays out what many consider is Johnson's Plan B or perhaps his ultimate strategy: "Boris Johnson calls a general election and uses the narrative, 'It's the people versus Parliament. I tried to deliver Brexit and Parliament stopped me, so therefore, vote for me and give me a bigger majority and I'll be able to deliver what you want,' " Lowe says.

Under this scenario, Johnson would run a classic populist campaign against the bureaucrats in Brussels while painting the U.K. Parliament as anti-democratic and defying the result of the 2016 Brexit referendum. Like most observers here, Lowe sees Johnson as a highly flexible political animal.

"I think the only question that really matters to Boris Johnson is 'How do I remain prime minister?' " says Lowe, "and everything else he's doing right now flows from that."