Ed Miliband will tell business leaders that it is right to press for reform in some areas while remaining "passionate" that membership of the Union is firmly in the national interest.
Quitting the EU would leave Britain "competing on low-wages and low-skills, an off-shore low-value economy, a race to the bottom", pushing the economic, political and strategic case for membership, he told the The Sunday Telegraph.
Crises in the eurozone, soaring unemployment, and a budget more suited to the 1950s than the 21st century had however shaken confidence in the Union.
More top news
Two brothers who rescued a bald eagle from a trap managed to take this selfie with the bird before it flew away.
A woman is being hunted by police after posting a picture of her dog's mouth duct-taped shut because it wouldn't "shut up".
Britain is to be lashed by gales of up to 70mph today as Storm Clodagh makes its arrival from the Atlantic.