LONDON (Reuters) – Boris Johnson has 100 backers and could be on the ballot to succeed Liz Truss as Britain’s prime minister, Sunday Times Chief Political Commentator Tim Shipman said on Twitter, citing an unnamed source close to the former prime minister. The BBC and Sky News also reported separately that Johnson, who arrived in London earlier on Saturday after a holiday in the Caribbean, now had more than 100 backers. While Johnson has not officially declared he is running in the contest, his supporter and Conservative lawmaker James Duddridge said on Friday that Johnson had told him he was …