By William Turvill Google is struggling to persuade some of America’s largest publishers to sign up to its News Showcase aggregation scheme, an investigation by Press Gazette has found. Armed with a $1bn budget to pay publishers for the use of their content, Google unveiled Showcase nearly 15 months ago. The programme has gone live in 14 countries and has more than 1,000 publication partners, including leading titles in the UK, Canada, Australia and Germany. But the service has yet to launch in Google’s native, and most important, market – the United States. Press Gazette understands that Google started making approaches and contract offers to US