Google is launching a campaign to line up TV networks’ support for its new Google TV software, but many remain reluctant to partner with a service that encroaches on their turf.

The service will allow people to watch and search cable, satellite and Web programming—as well as access regular Web pages—through TVs and set-top boxes that incorporate new Google software. The first devices, made by Sony Corp. and Logitech International SA, are due out this fall, marking another tug-of-war between tech companies eager for new content and media companies worried about giving it away. More>>