President Barack Obama said Britain would lose global influence if it left the European Union, providing a boost for Prime Minister David Cameron as he battles members of his own party who want to quit the bloc.

“The U.K.’s participation in the EU is an expression of its influence and its role in the world,” Obama told a joint news conference at the White House after talks with Cameron today. Cameron’s strategy of attempting to renegotiate the terms of membership before a referendum in 2017 “makes some sense to me,” he said. “You probably want to see if you can fix what is broken in a very important relationship before you break it off.”

Cameron’s three-day visit to the U.S. that began today has been overshadowed by wrangling at home over Britain’s relationship with the 27-nation EU. Earlier, he rebuked Tory lawmakers have already decided that Britain should withdraw.